text:
On the Lighter Side => New Theories => Topic started by: truthseeker67 on 03/09/2013 23:39:43
Title: thrust does not work in space
Post by: truthseeker67 on 03/09/2013 23:39:43
the reason why thrust cant work is simple
thrust equals = weight in order to have weight we need gravity.
see its like this in space everything weighs nothing so i would say a rocket weighs 0
or put like this rocket =0
thrust=0 because without gravity there is no weight behind the thrust
to cause a reaction so no movement would take place.
on earth if you sit in a chair that has wheels on it and throw a heavy ball you would
move back, and guess why of course because of gravity.....see gravity makes the ball weigh something but if you did the same thing in space you wouldnt move because you and the ball weigh nothing at all .
Title: Re: thrust does not work in space
Post by: Pmb on 03/09/2013 23:50:27
Quote from: truthseeker67 on 03/09/2013 23:39:43
You're quite wrong. Space vehicles use thrust in space all the time so you're wrong merely by observation.
Anyway, that is not what thrust is. Thrust is the force exerted when mass is ejected which then has momentum. Since momentum is conserved there must be a back reaction on the rocket expelling the mass. That's Newton's third law. See http://en.wikipedia.org/wiki/Thrust
Thrust has absolutely nothing to do with gravity other than a rocket which has thrust can overcome the force of gravity and escape the gravitational pull of a gravitating body.
look when water comes out of a hosepipe with high pressure it is simply chucking out
weight, and thrust is weight why do you think rocket engines are said to create pounds of thrust, so then what are pounds.....see pounds are weight. the explosive gasses of a rocket engine on earth are chucking more weight out than what the rocket weighs thats why it goes up. In space the water and the hosepipe wouldnt have any weight so no recation would take place . Look have you ever asked yourself why all the satalites and space station included are all only in orbit, there is not one item of any sort further than orbit because they cant get there. they call something a space station but in fact it is not in true space it is still in the earths boundarys which we call orbit and guess what thrust works there and guess why?
Post by: CliffordK on 04/09/2013 00:44:26
Keep in mind that there is no true "zero-gravity", at least with respect to the space where we've sent rockets and space ships. See the wikipedia page on microgravity (http://en.wikipedia.org/wiki/Micro-g_environment). The gravity in low earth orbit (where the Hubble and International Space Station are) is just about the same as it is on Earth.
The effect of weightlessness is that of constant freefall, either with an object in orbit such as the satellites around Earth, or coasting in a non-orbital trajectory like the Voyager probes.
In fact, one way to provide artificial gravity in space would be to provide constant thrust, except that we don't have the technology to provide significant amounts of thrust for long periods.
I'm, not quite sure why rockets in the USA are rated with pounds of thrust. Perhaps Newton's of thrust would be a better measurement which would indicate a force applied to a mass through a distance for a period of time.
i live in the UK and i relate to thrust being in pounds but Newton's are in the metric system. Since it seems to be the USA that makes a lot of rockets going everywhere or nowhere i think pounds fits the bill here. its just model jet and rocket, pulse jet engines are often in pounds of thrust, Oh yes as long as we are within the earths atmosphere the rocket engine which is chucking out thrust, weight, pounds more than it weighs to get up there is acting with two important things Gravity is needed to give the thrust weight, imagine seeing a flame out the back of a rocket with no weight no substance behind it just like a blow torch a flame without any force behind it that's not going to move much is it .then we come to the next important thing its called air or atmospheric gasses. the thrust of a rocket engine has to have something to push against it cant push against its self. That would be like bolting an engine with a prop on it to a boat and pointing it at the sail do you think the boat would move? Of course it wouldn't we have created a sealed circuit where no reaction can take place. so in orbit the elements needed for trust to produce momentum still exist, but in true space or outside higher orbit there is a vacuum no air no gasses no gravity not much of anything for thrust to push against and i simply don't believe a rocket can push a against its self using Newton's third law. In space there is no third law and if i believed there was i wouldn't of started this topic. Not even the rocket plane that was built the x 15 could get free of orbit and into true space when it should of been more than worthy to get there, self contained oxidizer plenty of fuel, plenty of thrust but what happened when they tried to break through the thrust died back and they were forced back to orbit like everything else that's why there's so much space trash round the earth they cant put the satellites further out because they know its impossible
Consider two blocks with a spring under compression between them, but not attached to the blocks.
[ Invalid Attachment ]
In a frictionless environment (on ice, in space, on an air table, whatever), release the spring, and one block goes right, the other goes left. BOTH blocks move in opposite directions.
That is essentially how a rocket engine works, except the exhaust of the rocket engine (mass) is expelled at high velocity. While only a little is released at a time, for a large rocket, more mass is lost through the burning rocket fuel and forcing it out at high velocity behind the rocket than the mass of the remaining rocket structure.
Space Junk is around Earth because most of our satellites and space missions have been launched to the area around Earth because that is where they are needed, and it is easier to access. There have, of course, been a couple of missions to the moon (still technically within Earth's gravity), but probes have also been sent to all of the planets, a couple of comets, and even to dwarf planets, as well as being put into orbit around the sun. The Voyager probes are now leaving the solar system, and while still under the influence of the sun's gravity for the next thousand years or so, eventually they will eventually pass beyond the sun's gravity, and head towards the next star.
hi cliff nice illustration the coiled spring under tension would work almost anywhere no doubt about it even in deep space i expect. But the spring under tension has two surfaces to act on and push against, pushing on both sides at the same time now you have a reaction. but going back to the thrust coming out of the engine in my mind space being a vacuum and void of anything to push on means that the blast energy would just be absorbed out into space thrust would have to fire up against something.I see a vacuum as wanting to suck the guts out of something including the thrust leaving the rocket trying to push against its self again. And if we took one block and could compress the spring against one side of the one block in space and release the spring what would happen to the block do you think? would the block leave the spring or would they leave each other or would the block stay and the spring whiz off . Thing is i don't know if we can compare a block and spring to thrust because of the way the energy is released like for example if i was in space and i was holding a cannon ball and flung it away from me very fast do you think i would go in the opposite direction. So lets say that i am the block of wood and the cannon ball is the spring also noting in space me and the ball are not going to weigh much if anything at all and me pushing against the ball as fast as possible really my hands are acting as the spring part, when this is done on earth you get recoil so i get pushed back but in space things have mass but no weight to act on each other so where is the reaction going to come from to push me back. Momentum in space is a strange thing take a petrol engine the way the crankshaft is weighted and balanced to stop at a certain point. In space that weighted crankshaft wouldn't know where to stop if it could run because it wouldn't weigh anything. So the weight that is produced in pounds of thrust by a rocket engine has got to have something to exert force against to get its forward motion. orbit provides that because it is still earths atmosphere, i mean there's all sorts of elements and various gasses the thrust can act against.
weight, and thrust is weight ..
You're confusing force with gravitational force. In Newtonian physics they are different things. Force and weight are different things. Please learn the difference.
yes the forces are different but lets get back to the thrust in space issue . could a water rocket under high pressure when forcing out its charge into space move forward, would it be said that the rocket would push itself away from its own charge rather than pushing against the void of space in order to move because on earth the charge of water would have weight behind it but would the charge of water in space have weight too!. like on earth a hosepipe will take off under thrust if not held down because its chucking out weight in the form of pounds of thrust . The more weight it chucks out the faster it wants to go up. Can this weight ratio apply in space where weightlessness dominates .
I think the point is that while you may not have weight when in freefall in space, you still maintain the mass which opposes change.
Is a Hydrogen/Oxygen engine a special type of high temperature/pressure water engine?
In a sense, the combustion of the hydrogen/oxygen does occur outside of the rocket. However, perhaps the idea is that the expanding gas doesn't "disappear" immediately, but presses against the rocket engine bell.
Post by: dlorde on 04/09/2013 14:14:42
You seem to be confusing mass with weight. Weight is the effect of gravity acting on the mass of an object. The mass is constant independent of gravity, but weight depends on gravity. On the moon, an astronaut has the same mass as on Earth, but weighs less because there's less gravity acting on his mass. In space, objects have no weight but still have the same mass. You can tell how massive an object is even in space, where it has no weight, by how hard it is to get it moving or slow it down; this is due to its inertia.
You've already had thrust explained to you - Newton's 3rd Law, 'for every action there is an equal and opposite reaction'. A rocket in space throws out exhaust and gets an equal reaction in the other direction. There's no requirement to push against space - it's the same principle as pushing someone away from you on ice, they will slide in one direction, you will slide in the opposite direction.
Post by: Kryptid on 05/09/2013 01:50:24
The fact that spacecraft have been sent to and landed on Venus, Mars and Titan proves that your reasoning is incorrect. That alone should tell you that there is a flaw in your argument (unless one were to propose some kind of inane conspiracy theory about how all of the space agencies of the world have faked these missions...).
Even in the vacuum of space, no doubt igniting tons of propellant in the exhaust bell creates transient pressure.
Post by: Lmnre on 05/09/2013 17:18:40
Quote from: dlorde on 04/09/2013 14:14:42
In space, objects have no weight but still have the same mass.
...and so they develop equipment and methods to measure mass, such as people's masses (http://www.youtube.com/watch?v=8rt3udip7l4) as part of monitoring their health. Quite the high-tech "bathroom scale". What you don't notice is that, according to Newton's Third Law of Motion, as the person moves "up" and "down", the ISS is moving (ever so slightly) "down" and "up".
thing is man never went to the moon in the first place alone other planets. For a start when you enter into space the radiation is so strong nothing could survive the trip and live to tell the tale. Watch this folks even if you think its not true its still good from a science fiction point of view enjoy.
//www.youtube.com/watch?v=1Ra40cCm-BQ
thing is man never went to the moon in the first place alone other planets. For a start when you enter into space the radiation is so strong nothing could survive the trip and live to tell the tale.
Of course, that's complete nonsense. Funny though.
Post by: alancalverd on 05/09/2013 23:20:00
thrust equals = weight
Not true. Never mind space flight, just look at an aeroplane. Thrust acts forward (assuming the propellor is in the usual place, doing its normal job), weight acts downward. Orthogonal vectors cannot be equal.
Even if your radiation claim was true, it ignores the fact that such radiation would not be an issue with the unmanned probes that have been sent to other places in the Solar System. What about the Venera probes that landed on Venus? The Pathfinder, Phoenix, Vikings 1 and 2 and other landers on Mars? Huygens on Titan? The Luna landers on the Moon? Those machines had to get there somehow, and they didn't do it by teleportation.
The radiation dose for the Apollo moonshot astronauts was less than the allowable yearly dose for nuclear workers. Full details are in this NASA report (http://lsda.jsc.nasa.gov/books/apollo/s2ch3.htm).
could you imagine all the heat the vessels would absorb in space even with the protection they claim they have, keeping them cool just on batteries or whatever i know they use materials to reflect heat but even a mirror in the sun can get very hot.The outer shell of a spacecraft is acting a bit like a flask but sooner or later that heat is coming through. Read about the damage and problems the sun and radiation causes the satellites in orbit.
It's all well known and entirely predictable (apart from the occasional solar flare, but we have a pretty good idea of the maximum intensity of those). We use radiation-hardened components in near-earth satellites and design circuits to fail safe when irradiated - a common problem with nuclear power plant and some military equipment.
Obviously the side of a spacecraft facing the sun gets hot, just like the planets do. But what do you think happens on the other side? Unsurprisingly, if you rotate a vessel somewhere near the earth's orbit, it ends up at somewhere near the temperature of the earth.
If you really are a truthseeker, try starting from the obvious, the commonplace, and your own observations. Anything else is of dubious validity.
So you really believe that no spacecraft have ever been sent to other planets? That there's some giant conspiracy in place that's been going on for over 50 years in which no whistle-blowers have ever come forward, no one has slipped up, there have been no leaks, etc? Let's not forget that the United States is not the only country that has sent spacecraft beyond Earth orbit, so this has to be a world-wide conspiracy with cooperation between multiple space agencies (including Russia and the US during the Cold War...). How is this rational?
Forget it guys, you can't argue with this type.
Post by: lean bean on 06/09/2013 17:26:34
the reason why thrust cant work is simple thrust equals = weight in order to have weight we need gravity.
truthseeker67
According to your own logic here, both rocket and fuel have weight in interstellar space.
If your rocket has mass,then it's gravitating, 'pulling' on the fuel in the tank, or the hot gaseous 'stuff ' shooting out the rear. So, because of this gravitating 'pull' your fuel as a weight relative to the rocket.
The fuel, hot or cold, has mass, so, it 'pulls' on the rocket, and the rocket has a weight relative to the fuel. Have I got your logic right? I'm forgetting about speeds here.
After seeing the evidence of fakery in NASA pictures and videos I decided to investigate the theoretical basis of rockets in space. What I found on the Internet were mainly tricks, frauds and sleights of hand, name-calling and attacks used to confuse the issue and hide the facts. Bypassing all of that and doing original research I have come to the conclusion that rockets cannot function in space according the descriptions/formulas used by NASA and related parties.
With neither theory on its side nor reliable, verifiable, repeatable scientific experiments on its side the idea of rocket thrust in my estimation remains a fiction presented to the world as an achievement: a modern day Marco Polo story.
I will try to present my findings with a minimum of maths and formula as these are often used to drawn us into traps, causing us to argue the minutiae of red herrings or chase ghosts.
There are 4 major ideas on presented on the Internet, including NASA web sites, as to how rockets generate thrust in space
1. Newton's 3rd Law : for every force there is an equal and opposite
2. Newtons's 2nd Law : Force = Mass x Acceleration
3. Conservation of Momentum
4. The use of a specialized nozzle to accelerate the gas inside the ship, concentrate and aim the gas jet.
The problem with applying Newton's 3rd is that the rocket's propellant does not generate force in a vacuum according to the laws of physics and chemistry. If the force of the propellant is 0 then Newton's 3rd states that
Force on Rocket=-Force of Gas.
If Force of Gas = 0 the rocket does not move.
Why doesn't the propellant generate any force, it's expanding, right?
There is something known as "Free Expansion" or the "Joule-Thomson" effect, named after James Prescott Joule and J.J. Thompson two of the founders of the field of Physical Chemistry.
http://www.etomica.org/app/modules/site ... ound2.html
Free Expansion states that when a pressurized gas is exposed to a vacuum the gas expanding into the vacuum without any work being done. The gas is not "pulled" or "sucked" into the vacuum nor is it "pushed" out of the high-pressure container. In other words no work is done, no heat or energy is lost.
This result has been experimentally verified numerous times since its discovery in the 1850's.
[for example a paper in the Journal of Physical Chemistry from 1902: http://pubs.acs.org/doi/pdf/10.1021/j150043a002]
As if Free Expansion wasn't enough to invalidate the theory of rockets producing a force in a vacuum there is also a result from thermodynamics:
Work = Pressure x Change_in_Volume
that is easily found searching for "W=PV"
http://lsc.ucdavis.edu/~ahart/Alicia2B/Thermo.pdf
If the pressure of a system is 0 then the work done by the expanding gas into that system is 0. Gas expanding in a vacuum doing no work agrees with Free Expansion. This can also be understood as the gas meets no resistance as it exits into the vacuum and thus transfers neither heat nor energy to its surroundings. If the gas loses neither heat nor energy then it has done no work.
At this point we have a rocket with high-pressure gas generated from liquid fuel that can release the gas into a vacuum but has no way to produce a force while doing so. As soon as the nozzle is opened the gasses escape without doing any work. Therefore the 3rd Law is rendered useless.
As it turns out NASA does not fall into the 3rd Law trap (nor does it go around correcting all the sites who do) instead claiming that thrust of a space rocket is generated using what I call The Wrong Formula, an egregious farce of Newton's 2nd law.
To recap: Newton's 3rd Law, the number one response on the Internet to how a rocket generates thrust in space, is invalid in this context. NASA itself avoids using Newton's 3rd Law as the reason why their rockets work so well in space choosing to use Newton's 2nd Law instead. NASA's use the 2nd Law is equally invalid and in fact a hideous misrepresentation of the laws of the laws of physics that would give a freshman college student a failing grade yet earns NASA an "A" thanks to its pretty pictures, dramatic story lines, and gutsy champions, the astronauts.
Wow. So how did all those satellites get positioned up there, outside the atmosphere?
Are all the American, Russian, Chinese, Japanese, Indian, and European (did I miss anyone?) space shots faked?
Why would they do that? - I feel so cheated...
of course the satellites are up there if you fired a canon ball from a massive gun that be up there too heheh only joking .
Tom Wolfe's book "The Right Stuff" documents high altitude flight tests with rocket powered aircraft that would invariably fail in the thin air and plummet back to earth. Chuck Yeager almost died in a NF-104A rocket plane failure while attempting to set a height record. These planes were liquid fuel rockets and not air-fed jets.
Why would NASA claim to be able to send rockets into space when the USAF couldn't get the same technology into even the upper atmosphere?
Why did Chuck Yeager not join the space program? Did he know it was a hoax?
And like I said the x15 rocket plane was more than worthy with its own contained
Oxidizer but couldn't make the trip.
I think its time to wake up folks and smell the coffee. I know it's a very elegant fantasy to think of space travel but it only happens in the movies so enjoy them.
Of course you're joking; because, apart from the satellites, you also have to account for these missions (http://www.extremetech.com/wp-content/uploads/2011/11/50_Years_Space_Exploration1.jpg).
Truthy #4
the thrust of a rocket engine has to have something to push against it cant push against its self.
The problem with applying Newton's 3rd is that the rocket's propellant does not generate force in a vacuum according to the laws of physics and chemistry.
Free Expansion states that when a pressurized gas is exposed to a vacuum the gas expanding into the vacuum without any work being done. The gas is not "pulled" or "sucked" into the vacuum nor is it "pushed" out of the high-pressure container. In other words no work is done,
Imagine a hollow cube in interstellar space, at the centre of this cube there is an explosion. Each inner wall of the cube will receive an equal pressure (push) from the expanding gasses of that explosion, and so the cube does not move in any direction.
Take away one wall of that cube, and repeat the central explosion.
Again, the gaseous particles hit all walls with equal pressure except the missing wall. The pressure on the wall opposite that missing wall is not countered, and so the cube moves in the direction opposite to the missing wall.
Thrust in interstellar space.
hi leanbean i can see what you mean with the cube it just when i look at photos of satellites in space the backgrounds are always completely black no stars are ever present in the pics look at this one of the Hubble telescope taken from the shuttle heres the link look at the pic and enlarge it see what you think http://en.wikipedia.org/wiki/Hubble_Space_Telescope
... when i look at photos of satellites in space the backgrounds are always completely black no stars are ever present in the pics look at this one of the Hubble telescope taken from the shuttle heres the link look at the pic and enlarge it see what you think http://en.wikipedia.org/wiki/Hubble_Space_Telescope
The brightness of the light reflected from the satellite that means the exposure is necessarily too short to register the starfield.
Check out this site (http://www.clavius.org), it will explain a lot of stuff you don't seem to understand, such as the absence of stars in many photos (http://www.clavius.org/stars.html).
Blimey! So my transatlantic phone link, GPS navigation systems, and even television, are all the products of a massive conspiracy!
Fair enough, but why do the fakers and conspirators take so much trouble to help me run my business, fly and drive from point to point, and watch The Simpsons? And how do they find the time to do it for everyone else as well? And why do they bother to introduce such long transmission time delays, when I would have been perfectly happy thinking it was done with a direct cable? It's a great service, and ridiculously cheap. I'm amazed.
I watched the lunar conspiracy theory video. They did make some interesting points. However, one might be tempted to ask where all the moon rocks came from???
Here are some "new" photos of the landing sites on the moon.
http://www.nasa.gov/mission_pages/apollo/revisited/
http://www.nasa.gov/mission_pages/LRO/news/apollo-sites.html
when i started this post i never doubted that satellites were not up there. Of course i know they orbit the earth. The topic is thrust doesn't work in space true space and all the satellites are in lower orbit where i do believe thrust works. I think people either haven't read my post from the beginning or have read it and forgot what i said only a page ago.
Oh yes Cliff was looking at what you posted me and was also checking out the camera thing i can see that the correct shutter speed and exposure time must be right for a given situation in order for small illuminated objects to show in background.
So, uniquely among mankind, you do not understand the principle of conservation of momentum, but you simultaneously believe that satellites are in orbit.
You should ask yourself, therefore, what is keeping them up there? Everything I have ever flown has either been lighter than air or fitted with wings. Do satellites, which are heavier than air and have no wings, have some kind of magic power that we ordinary aviators and engineers don't know about? Why don't we use it for everyday travel?
when i started this post i never doubted that satellites were not up there. Of course i know they orbit the earth. The topic is thrust doesn't work in space true space and all the satellites are in lower orbit where i do believe thrust works.
If thrust only works with air to push against, it would become less efficient with altitude, so that at low Earth orbit, there wouldn't be enough atmosphere for thrust to be effective. That would mean a rocket would need so much propellant to reach orbital velocity or escape velocity, it would never get off the ground.
Returning to reality - what about the geostationary communications & weather satellites at 35,786km out? they need an orbit change to achieve circular geostationary orbit (see Geostationary Transfer Orbit (http://en.wikipedia.org/wiki/Geosynchronous_transfer_orbit)). This requires a thruster (rocket engine) burn - in space.
What about the Solar and Heliospheric Observatory (SOHO),the Global Geospace Science (GGS) WIND, and the Advanced Composition Explorer (ACE) in unstable halo orbits at the L1 Lagrangian point (http://en.wikipedia.org/wiki/Lagrangian_point)?
Both geostationary and L1 satellites require orbital station-keeping (http://en.wikipedia.org/wiki/Orbital_stationkeeping), due to orbital instabilities (other satellites also need occasional orbital or attitudinal adjustments), and this also requires the use of thrusters - which are rocket engines.
Assuming you are serious and not trolling, your persistence in the face of overwhelming contrary evidence has the hallmarks of delusion - a delusion is a belief held with strong conviction despite superior evidence to the contrary (http://en.wikipedia.org/wiki/Delusion).
Quote from: truthseeker67
Read a book and learn that he wanted to be an astronatu but wasn't qualified. I.e. NASA required astronauts to have a college education, not simply a highschool education, to be an astronaut. Simple, huh?
I've ignored the rest of your posts because it's crystal clear to me that you have absolutely no idea about what you're talling about. Every single thought that you've posted is wrong.
Let this one go, folks. It's ot worth your time arguing with him. He doesn't know enough basic physics to carry on a simple conversation.
Why do you link to a photo of Hubble, which is in low earth orbit, and then make the point of saying there's 'no stars' in that photo. Have you changed your mind now and saying things can't even be in low earth orbit because the absence of stars proves hubble is not in space at all??
Truthy
Ttruthy
hi leanbean i can see what you mean with the cube
So I didn't convince you about thrust in interstellar space? aho. What's do you think is wrong about the cube explanation of thrust?
Okay. It's time, once and for all, to show in detail why is wrong. In the very first sentence in this thread he writes
His error is the invalid assumption that "thrust equals weight." I explained this all too simple fact to him and he didn't understand it. Nobody can use an invalid assumption to prove anything. He tried to prove me wrong by arguing, wrongly, that
weight, ..
truthseeker67 = A hosepipe does not "chuck out" weight since that's a meaningless statement.
And your comment right here requires special attention. You admit that water coming out of a hose causes force to be exerted on the hose in the direction opposite to the direction the water is coming out of. The problem with your argument is that the force exerted by the water is independent of the direction the water is ejected. It therefore cannot depend on the force of gravity and therefore cannot depend on gravity
…and thrust is weight ..
This invalid belief you keep trying to pass on is the source of your misconceptions on this topic. I.e. you simply don't understand the meaning of the term "thrus" or "gravity"
.. do you think rocket engines are said to create pounds of thrust,…
I know that they do. It's you who don't know why they do.
… so then what are pounds …
I'd say to look it up but you keep refusing to do so. You don't seem to like using dictionaries. Probably because they prove you wrong.
The term pound is the British unit of force whereas the SI unit is the Newton. See? You don't know what it mean!
.....see pounds are weight.;.
Why don't you do so yourself?
And your example contradicts your assumption since the water in a hosepipe will work even in the absence of gravity. Had you taken my advice and actually looked up the term in a dictionary or a physics text then you'd have learned that. But you didn't, did you? You didn't want to look it up because you'd see that I was right and you were wrong!
If you knew how a hose spitting out water caused there to be a force exerted back on it then you'd understand the error of your ways. Since you don't know why then that's proof enough for everyone to understand why you're so wrong.
There are two definitions of the term weight. One is defined at http://en.wikipedia.org/wiki/Weight
weight - the weight of an object is usually taken to be the force on the object due to gravity.
The other is defined in The equivalence principle and the question of weight by Kenneth Nordtvedt Jr., Am. J. Phys., 43(3), Mar. (1975) [http://link.aip.org/link/ajpias/v43/i3/p256/s1] which reads
The weight of a body is meant to be the forces (e.g. the compression of a spring scale) required to either support the body in a gravitational field (gravitational weight) or to accelerate a body relative to an inertial system.
..because without gravity there is no weight behind the thrust.
Oy vey! You keep saying this and it's not true.
The rest of what you say is nonsense.
could you imagine all the heat the vessels would absorb in space even with the protection they claim they have, keeping them cool just on batteries or whatever i know they use materials to reflect heat but even a mirror in the sun can get very hot. The outer shell of a spacecraft is acting a bit like a flask but sooner or later that heat is coming through. Read about the damage and problems the sun and radiation causes the satellites in orbit.
All of this is extremely wrong. Scientists knew how wrong this was long before they put satellites into orbit. And you admit that scientists put satellites into orbit so you must know how wrong it is.
The complete explanation regarding cosmic rays is given here
http://en.wikipedia.org/wiki/Health_threat_from_cosmic_rays
The other forms of radiation spoken about in this context comes from forms. They are;
Electromagnetic radiation (gamma rays, x-rays, ultraviolet rays, light waves, infrared rays, radio waves)
Beta radiation - electrons
Alpha radiation – nuclei of He atoms
The most obvious reason why truthseeker67 is wrong comes from his own example; the water hose. Let the water coming out of a firehose be pointed onto and at a person. The force on that person, i.e. the force exerted on the person by the water, would cause the person to topple over due to the force the water exerts on the person. This is due to the time rate of change on momentu that the person exerts on the water.
The fundamental problem seems to be that our correspondent does not understand the difference between mass and weight. Therefore any talk of force and momentum is wasted on him.
Clearly the last 2000 years of scientific discovery and education have not penetrated the fog of misunderstanding perpetrated by Aristotle, Galileo died in vain, and Newton was just another farmer with an orchard.
Fortunately for the rest of us, Newtonian physics seems to work pretty well everywhere. But there's no point in arguing against a conviction. Just beware of anyone calling himself Truthseeker who offers to fly, drive or shoot anything for you.
Quote from: alancalverd on 11/09/2013 11:24:02
alancalverd, my good man! I couldn't have said it better myself, so from now on I won't. Thank you so much!
Let's try to boil down just why a properly executed fuel explosion within a craft would not be able to move the craft.
If there were a successful chemical explosion or comparable force outside the craft, and at its rear, it should propel the craft forward at least a small amount. However, if the explosion is internal — as we are led to believe — this would cause equal work in all directions and hence do nothing except stress the inside of the craft.
Only by somehow releasing a strategic percentage of the explosion to the infinitely permissive vacuum would the remainder do any work against the ship and cause it to move. But how could this be accomplished using the same rockets that are meant to propel the ship via thrust against air pressure?
Given that these "maneuvering in space" rockets are different rockets for a different purpose, safely nestled amongst the original Earth-based rockets, we are supposed to believe that the force of their internal explosions alone is moving and directing the craft in space, rather than thrust against anything as it works on Earth. So I guess we are meant to believe that NASA has found a way to transition their crafts' functions — as they ascend — from Earth physics to vacuum physics. I guess this would be a delicate process given that in the vacuum:
- conventional explosions would not be fed by adequate oxygen
- air pressure could no longer be used for lift
- lack of pressure outside the ship would cause extreme stress on the inside of all mechanisms with pressure
In other words, the amusing little jets of gas we see exiting the craft for 'course correction' cannot possibly be what they look like: just a gas being released into the vacuum. They must instead be representations of an internal, highly controlled and precise explosive force aimed at the inside of the craft itself, and the "jet" pictured is merely the residual energy that must escape to prevent the chamber from blasting open?
Do we have any schematics of how the.. "we are in the vacuum now" jets are supposed to work, and fit in/amongst the other functions of the craft?
... how could this be accomplished using the same rockets that are meant to propel the ship via thrust against air pressure?
There's your problem.
Rockets work the same way (action-reaction) in air or space. They don't work better by 'thrusting against air pressure'; if anything, air resistance against a rocket makes it less effective in air, requiring more fuel.
The fuels used in rockets don't need external oxygen (neither do most 'conventional' explosions); solid fuels have an oxidizer mixed in, liquid fuels are usually hypergolic (http://en.wikipedia.org/wiki/Hypergolic_propellantl), i.e. two liquids that combust when mixed. Some thrusters may use compressed gas or electromagnetically accelerated plasma (ion engines).
This is all basic school-level physics.
If there were a successful chemical explosion or comparable force outside the craft, and at its rear, it should propel the craft forward at least a small amount.
The explosion chamber of a rocket engine is open to space on one side via the nozzle.
However, if the explosion is internal — as we are led to believe — this would cause equal work in all directions and hence do nothing except stress the inside of the craft.
You forgot to mention the missing wall, so it is open to space. On a rocket that opening would be a nozzle or something bigger.
Thruthy
In other words, the amusing little jets of gas we see exiting the craft for 'course correction' cannot possibly be what they look like: just a gas being released into the vacuum. They must instead be representations of an internal, highly controlled and precise explosive force aimed at the inside of the craft itself,
Do you mean the explosive pressure on the front of the chamber is pushing the rocket forward because that forward thrust is not countered because of the rear opening in the chamber wall called a nozzle?
What was your point about the 'no stars' in the Hubble photo?
Quote from: dlorde
And that's the problem. His lack of understanding of what thrust is has led him to believe all sorts of things. I've made many attempts to get him to look up the meaning of the term but those requests were ignored. I have no idea why but I imagine that if I had to learn what they were then he'd have to admit he made an error. In this case it appears that he thought he could prove something known to be quite true as wrong merely by changing the definition. That's a mark of pseudoscience if I ever heard one!
someone just show me an experiment of a rocket working in a vacuum never mind the theory lets just see the reality .
Do you actually believe that every scientist here has a list of every experiment ever done in his mind readily recallable? Sorry but it doesn't work that way. Especially with something so simple that nobody needs an experiment to be done in order to know what will happen in a vacuum. I'm actually unable to understand how people think a rocket works in the atmosphere (but not in a vacuum).
To actually do such an experiment is very trivial. College class rooms have a glass bell from which the atmosphere can re readibly vacuumed out. A rubber hose can be left in. When air is let back in there will be a force on the hose from the air being let back in.
Analysis of the hoses motion will tell you if truthseeker67 is right or every single physicist alive today (including me) and their teachers are correct. I'm betting on every physicicist alive today. Especially since they understand nature and truthseeker67 is not even willing to look up the term "thrust" in a dictionary or provide a realistic argument for his guesses. I know that I'm right because I know elementary physics. This is simply the principle conservation of momentum at work. It's what makes a person recoild back when he's hit with a sack of potatoes when one is lobbed at him.
So, still not willing to learn physics yet, huh?
The experiment is demonstrated every time a rocket fires in space - which happens often. Satellites, probes, space labs - they all do it.
His problem is (1) he doesn't want to pick up a dictionary and look up the term "thrust" to see how it's really defined as opposed to how he wants it to be defined and (2) he thinks there is a worldwide conspiracy to fool him, especially when it comes to communications satilites and the GPS system. All he has to do is contact NASA and they'd tell him where those experiments were done for which satelites/rocket engines but that'd prove him wrong too. That's not his way it seems.
[quote author = dlorde]
Why show you 'videos/films' on the web, when you can just say they are using trick photography.
To read a description of an experiment and the given theory of why it works the way it does, is down to the reader's understanding of physics.
All people can do on the web is to offer acknowledged expert sites on such matters.
Or you may find 'non acknowledged' experts that have a good understanding and can lead you in the right direction to answering things.
You can say Nasa is using tricks, but that must be based on your personal understanding of physics to say Nasa is using tricks. So it's down to words not just pictures. :)
Why do airliners fly so high? Because a reaction-powered machine works better when there's less air around? Or because Ryanair has money to burn on fuel that would be saved by flying lower? If elementary concepts of physics are beyond you, perhaps you understand the concept of profit?
The scary thing is that he seems to find it plausible that there's a multi-trillion dollar global conspiracy, that started many years before he was born, involving people working in schools, colleges, universities, research & engineering labs, the economic, financial, design, and manufacturing sectors of the aerospace industry, audiovisual fakery, media broadcasting, Earth sciences, remote sensing, weather prediction, satellite communications, planetary probes, SatNav, GPS, other stuff I've missed, etc...
Wait, that's nearly everything, right? Wow, this thing is bigger than religion... and all to fool people like him (i.e. those who can't do simple physics). But why? That's the real question to answer!
Alternatively, maybe he's a beginner's physics course short of an education. An introduction to critical thinking wouldn't go astray, either.
But why? That's the real question to answer!
Because he's not willing to learn. Didn't you notice that he refuses to answer any direct questions about his knowledge of physics?
Quote from: Pmb on 15/09/2013 17:19:47
It's obvious he doesn't know (or pretends not to know) any physics; what I was asking him was why this vast global conspiracy is going on ;)
Which leads me to wonder whether the crossover point between conspiracy theory and plain paranoia is when the number of people involved in the conspiracy exceeds the number uninvolved it...
Yeah. I saw that. ;) I think that mostly people like that are truely serious. They have this thing going on where they think they know more than everyone one else, including scientists, because they put some thought into it and came to different solutions and therefore the scientists must be wrong!! They refuse to learn physics because they assume it will corrupt their mind with nonsense. Ha ha ha!
By the way buddies Airplanes use less fuel at high altitude than they use at low altitude, because the air is thinner at high altitudes and therefore produces less air resistance to slow the airplane down thought i would explain that using my useless physics, so airplanes are more efficient at higher altitudes.
how can you believe NASA about anything. when a flag blows in a breeze on the moon and so many other things that are simply not correct, too many inconsistencies for my liking and a Luna module that looks like an activity scene made by primary school children and not to mention no blast crater from that all powerful rocket thrust,that didn't even leave dust on the feet of the lander how strange could that be.
So does a jet aircraft become most efficient in space where there is no air resistance at all?
What about propeller driven planes? more efficient or less?
What do you think is the main difference between rocket engines and jet engines (http://www.qrg.northwestern.edu/projects/vss/docs/propulsion/3-how-is-rocket-propulsion-different-from-jet.html)?
how can you believe NASA about anything.
We have no reason to believe they have anything to hide or anything to lie about. You're delusions and distrust with NASA are based on your ignorance of science. You, on the other hand, keep avoiding direct questions so we have every reason assume that you're hiding something. Plus many of us as scientists and know what we're doing while you on the other hand have no idea about science whatsoever.
And then there's the fact that Newton, Einstein, Maxwell, Galileo and Kepler were all around doing their thing long before NASA existed. Newton postulated his laws and demonstrated that they were true even before the USA was born.
I'm begining to feel like a school kid by arguing with him since that's the way he argues, don't you a bit?
You'll find the answers here (http://space.about.com/od/frequentlyaskedquestions/tp/LunarLandingHoax.htm).
It certainly feels like I'm talking to a school kid - one that's deliberately playing dumb.
He's got all the information he needs now; I suggest we leave him to it.
One more. The article you linked to said "Did you think of an issue I didn't address? Send me an email and I will be sure to add it." so I did. Here is my response
We went to the Moon to at the height of the cold war so the Russians were keeping a close eye on those rocket launches. The radio transmissions from the Moon to Earth could not have been faked. They had to be coming from the moon. Had we tried then the Russians would have pointed out to everyone in the world that the transmissions were not comming from the moon.
He won't be able to explain that, that's for sure. And he won't even bother trying (since he never does).
So presumably a rocket-powered aircraft, which doesn't need air to burn its fuel, would became increasingly efficient as the air got thinner, until....oh bugger, this is leading towards common sense. Obviously all the world's airlines have got it wrong, or are being paid by NASA to fly at uneconomic altitudes in order to cover up the global conspiracy about space flight.
The interesting thing is that not only the USA but Russia, the EU, China, India, Japan, and Korea are all part of the same conspiracy. Why? Because they recognise that Isaac Newton was the Antichrist.
alancalverd - I really don't think that he gets the thing about planes at higher altitude.
This page might be of some interest: http://rationalwiki.org/wiki/Moon_landing_hoax#Evidence_for_a_conspiracy (http://rationalwiki.org/wiki/Moon_landing_hoax#Evidence_for_a_conspiracy)
It turns out that truthseeker67 is really an economist who claims that his hobby is cosmology. His site is here http://www.eioba.com/niebieskieucho/articles
truthseeker67 M'man. I love the doo! :)
Post by: bizerl on 16/09/2013 07:15:53
Call me a sicko, but man I find these threads entertaining!
If there's less air and therefore it is closer to being a vacuum, wouldn't the jets start to fail? After all, "thrust does not work in space". [:)]
I like the way that rockets need something to push against and therefore wont work in a vacuum, but when you push a large metal construction against something as solid and tangible as, oh, I don't know... air!, you can break the sound barrier several times over!
I guess, truthseeker, that if you admitted to the truth, you'd have to change your username.
Quote from: bizerl on 16/09/2013 07:15:53
I hope you're not on his side and believe that rocket's need air to push on? That's quite wrong. It makes no sense for the gases to know that they're going to push on air before they leave the combustion chamber and not reflect off of the interior walls and thus exchange the momentum of the gas with the momentum of the walls of the chamber? truthseeker67 is unable to grasp science or engineering, I hope you don't think the same way? It looks like you're joking but I wanted to make sure.
truthseeker67 - What are the odds that you're learn about how a rocket engine works and stop all this nonsense that all physics and physicists are wrong for some mysterious reason and learn how a rocket works. See http://exploration.grc.nasa.gov/education/rocket/TRCRocket/rocket_principles.html
After you fail to do that I have a question that you'll be unable to answer correctly - How does a gun work and why is there a kick produced by the gun when its fired?
It turns out that truthseeker67 is really an economist
a discipline with no wrong answers, only "incomplete data in an inherently unpredictable market - but you wouldn't want to live in a controlled market, would you?"
who claims that his hobby is cosmology.
A field in which there is no possibility of a controlled experiment.
So he can't admit to talking nonsense, because that would jeopardise his career, and he won't be convinced by evidence because that implies experimentation rather guesswork string theory!
Quote from: Supercryptid on 16/09/2013 02:49:57
Thanks, that's a better one than the one I posted.
A graduate! here was I, thinking he was in his early teens...
Er, yeah! :)
Yes. Sorry Pete, I am joking. Also, whoever used the example of the cube with the missing side, i LOVE that example. It explained it beautifully.
I was reading back to the initial argument that thrust is based on "weight". It's a bit like me saying that "I reckon time is based on unicorns, and therefore I have just proved it doesn't exist - can YOU see any unicorns?"
It sounds like something out of a Douglas Adams novel where as soon as something enters weightlessness, it ceases to exist.
That's enough to prove to anybody that this is in fact that case, except truthseeker67 since he doesn't understand the concept in the first case.
If I haven't mentioned this before I'll do so now; he just can't grasp Newton's third law which states that wherever there is an action there is an equal and opposite reaction. See http://scienceworld.wolfram.com/physics/NewtonsThirdLaw.html
Note: There are exceptions to this law such as in electrodynamics, but not in this case.
Even if he did understand Newtonian physics, he still asserts that high orbits and free flight are the products of conspiracy and fakery, not real engineering achievements. He is clearly deluded. Any proper scientist knows that astronauts are borne aloft by noble thoughts and good fairies. I just wish he could convince my flight examiners, who always demand a very mundane demonstration of classical physics.
Forgive me for not paying close attention (LOL!) but I haven't been following him in detail. Where did he make such claims?
Stay awake boy
Look have you ever asked yourself why all the satalites and space station included are all only in orbit, there is not one item of any sort further than orbit because they cant get there. they call something a space station but in fact it is not in true space it is still in the earths boundarys which we call orbit and guess what thrust works there and guess why?
My bold
Quote from: lean bean on 20/09/2013 19:40:59
Not one item that isn't in orbit?
That adds up to at least 4. And, I think there are a few more, not counting those probes that have been sent to other planets such as mars, either landing on the planet, getting destroyed in the atmosphere, or inserted into orbit around another planet.
The International Space Station is in "orbit", rather than a non orbital trajectory because it was assembled in parts in space, and it is hard to get volunteers for Pluto flybys, especially when they turn the space heaters down to about 4K.
Quote from: CliffordK on 21/09/2013 01:03:44
I did put up a link to a nice poster of missions (http://www.extremetech.com/wp-content/uploads/2011/11/50_Years_Space_Exploration1.jpg) earlier.
He thinks that the Moon landings are a hoax and that NASA can't be trusted. He probably thinks that each and every one of those missions are faked and that there is a world-wide conspiracy in place to keep anyone from learning that.
Can anyone find anything about the natural jets on comets affecting the comet in some way?
I understand there must be some sort of cavern in which the contents quickly become gaseous in a confined space, resulting in pressure on all surfaces within the cavern, until one part 'gives'.
I could only find this...
Dr A'Hearn mentioned that if the comet "spins up" (i.e the jets increase the rotation rate), there is a possbility of it fragmenting (like C/2007 Q3). Will ground based scopes or the spacecraft continue to track 103P and for how long to see if this increase in spin rate occurs?
From NASA http://www.nasa.gov/connect/chat/hartley_chat.html
There is also a philosophical reason why NASA space rocketry is impossible: gas, via rocket engine exhaust or otherwise, has no effect, does no work, in a vacuum and cannot be used to move objects through space.
In 1852 scientist James Prescott Joule, for whom the unit of energy Joule is named, discovered that gas does no work in a vacuum http://www.etomica.org/app/modules/site ... ound2.html
If gas has an effect on objects in a vacuum I would expect to find an example in nature. All forces that man has access to exist in nature (including fission, fusion, chemical reactions, steam, etc...). We do not create forces we only discover them. In ancient times people thought a comet's tail was a gas jet pushing it along. Today I cannot find an example of an object moving through space via gas/jet propulsion although streams of gas and particles shooting into space exist. Saturn's moon Enceladus, for example, shoots a jet of water ice 500 KM into space. The diameter of the moon itself is only 500 KM. Does this jet have any effect? No. The jet as tall as the moon is wide goes harmlessly off into space. http://en.wikipedia.org/wiki/Enceladus_%28moon%29
That's not a philosophical reason. It's an explicitly physical reason - and, of course, it's nonsense. Posting broken links won't make it less so.
In 1852 scientist James Prescott Joule, for whom the unit of energy Joule is named, discovered that gas does no work in a vacuum
But a rocket in a vacuum is not a vaccum. The gas does work on the rocket, which is why it moves. Exactly as Newton stated, and as everyone who has ever designed, used or seen a rocket or jet engine, fired a gun, or even farted on an ice rink, knows perfectly well.
Philosophy? Get a life.
Today I cannot find an example of an object moving through space via gas/jet propulsion although streams of gas and particles shooting into space exist. Saturn's moon Enceladus, for example, shoots a jet of water ice 500 KM into space.
The jets on Enceladus were discovered by the interplanetary spaceprobe Cassini. How did Cassini get to Saturn and its moon Enceladus, if thrust doesn't work in space?
The plumes of water vapour were discovered by Cassini in 2005 and seemed to be related to the tiger stripes, but their precise source was unknown until now.
From http://www.newscientist.com/article/dn12770-source-of-saturn-moons-mysterious-jets-pinpointed.html (http://www.newscientist.com/article/dn12770-source-of-saturn-moons-mysterious-jets-pinpointed.html)
Ah, hoist by his own petard, methinks! :)
Gas does no work in a vacuum. It is only a passive participant and not an active force in space. We cannot use it as the basis for space travel. Bottling up gas and shooting it out of a tiny nozzle won't change its basic physical properties inside a vacuum, won't suddenly invalidate the laws of thermodynamics.
The theory of space travel based on gas jets and/or liquid propellants is a science fiction from the 1800's (Jules Verne et. al.) similar to the philosopher's stone and other magical, mystical pursuits we now look down upon. There is also the matter of the faked/fraudulent results of rocket pioneers such as Goddard which I will get to later.
If you ask why this is hoax is still going on it is because science has become a religion and NASA it's church. Specifically space travel is one of the Holiest of Holies. Try debunking a religion/cult and see how far you get. Once someone has been indoctrinated, invested themselves in its beliefs, it is nearly impossible for them to divest. For years I believed that space travel was the pinnacle of man's achievement. Now I have to wonder if any rocket has ever been past as far as we can throw it up from the ground.
... Once someone has been indoctrinated, invested themselves in its beliefs, it is nearly impossible for them to divest.
You've certainly convinced me of that !
I blame Newton, with his stupid 3rd Law.
But what about the jets from Enceladus discovered by Cassini? How did Cassini get there to discover them?
Gas does no work in a vacuum.
There's little point in carrying on this discussion if you don't read the replies. See #85 above.
I still want to see him directly address the cube argument that lean bean posted earlier. I find it kind of funny how he just brushed it off by saying "I can see what you mean with the cube" and leaving it at that. What? Can't find a good way to argue against it?
Good Lord! The man doesn't even know what it means to be in space or in orbit
Don't forget the many many satellites which are in geosyncrhonous orbit around the earth
There is also a philosophical reason ...
You've lost all credibility now that you've demonstrated a complete lack of understanding of nearly all areas of physics. You have nothing to share that I want to know and I'm certain everyone else feels the same way.
I realise I'm trying to enlighten a dead horse here but surely the gas itself is of little importance in the thrust of a spaceship. It is the explosion inside the ship (and therefore not even in a vacuum if it matters - which it doesn't) which drives the gas out through the jet on one side of the ship, but doesn't drive the gas out of any other wall in the engine and therefore the ship has no choice but to move in the direction that the gas is not leaking out of. This was the beautiful cube example from earlier.
You can't see that you've indoctrinated yourself to believe this fallacy about thrust in space blindly, without analysing the evidence around you and providing alternate theorys to explain the observations.
Quote from: bizerl
We've all accepted that as a given at this point.
Post by: CitronBleu on 24/06/2014 13:59:36
Hello TNS forum members,
I am interested in the problematic posed by this thread and wish to continue the discussion.
Quote from: beany on 15/09/2013 11:09:40
... it's down to words not just pictures. :)
Indeed, dear Beany.
Beany,
You assume time and space have no affect on the pressure produced against the wall opposite the missing wall by the explosion.
EDIT for clarity and grammar
Post by: PmbPhy on 24/06/2014 17:27:13
Quote from: CitronBleu
That's more than a mere assumption; it's an empirical fact and conforms to the laws of physics. Beany is describing the implications of Newton's third law – where there is an action there is always an equal and opposite reaction. See
http://scienceworld.wolfram.com/physics/NewtonsThirdLaw.html
The box in Beany' s example is a simplified form of a combustion chamber. Here's an even simpler example; if you through a ball against a wall the ball will bounce off the wall. That happens because the ball exerts a force on the wall. In response to the force exerted on the ball by the wall, according to Newton's third law, the ball exerts an equal and opposite force on the wall. That's one of the most well accepted facts in all of physics. This has been a well-established empirical fact for well over 300 years now. A great deal of what happens in nature is based on this fact.
The topic of this thread is how thrust affects a rocket. The opening post was off off about all of this. We (or at least I) corrected him. It should have been obvious to him that if he were right then all the rockets we've used to explore space would never have worked. The space shuttle wouldn't have been able to do all the things that we know that it did, we'd never have been able to send probes to Mars and most of the other planets in the solar system and we'd never have a Global Positioning System (GPS) that many people use nowadays. Very simply put, thrust works be bouncing material off of a one of the rear combustion chambers wall. This exerts a force on that wall which is then transmitted by the structure of the rocket to the rest of the rocket. Nasa has a web page online on this subject at
http://exploration.grc.nasa.gov/education/rocket/rktth1.html
Then we were insulted for our efforts with the claim that all cranks use, i.e. that we're all brain washed and can't think for ourselves, which is utter nonsense. Part of a physicists training is lab work where we experimentally explore what we learn in class. So we aren't merely told these things but are expected to observe them in the laboratory for ourselves. The person who created this thread based all of his claims with the assumption that is all based on the following assertion
thrust equals = weight in order to have weight we need gravity….thrust=0 because without gravity there is no weight behind the thrust to cause a reaction so no movement would take place.
which is quite wrong for the reason stated above. I have to say that it's quite irritating when people with essentially zero formal training in physics comes here to claim that all the physicists in the world during the last 300+ years are all wrong and only he is right. That's arrogance taken to the extreme.
Here's how he argued it
weight, and thrust is weight why do you think rocket engines are said to create pounds of thrust,
This statement proves that he doesn't know what he's talking about. Recall that NASA used rocket sleds to train astronauts. The sled had a rocket engine on it and when ignited the rocket engine exerted a force on the sled accelerating it down the track. The only weight operating here is the force exerted by gravity in the vertical direction. But the force on the rocket sled exerted a force in the horizontal direction which means according to him it wouldn't work. Also he thinks that the term pounds of thrust refers to weight which is quite false and actually a quite ignorant assumption. In the context in which he used it the term pound refers to a unit of force. See http://en.wikipedia.org/wiki/Weight and scroll down to where it says Pound and other non-SI units
In United States customary units, the pound can be either a unit of force or a unit of mass
We would have explained this to him but he didn't come here to learn. He came here to spread his "theory" which we explained to him was wrong and why it was wrong. He wasn't receptive to learning though.
Quote from: PmbPhy on 24/06/2014 17:27:13
That's more than a mere assumption; it's an empirical fact and conforms to the laws of physics. Beany is describing the implications of Newton's third law – where there is an action there is always an equal and opposite reaction.
Hi PmbPhy,
To what empirical fact are you referring ? To what laws of physics does this fact conform ? My assumption, shared by others, is that man has never achieved flight beyond a hypothetical 80-120 Km altitude.
This empirical fact must have been discovered early in the years which led to the formulation and then to the development of the space conquest narrative (Which I will call SCN for short.).
Three hundred years ? That is it ? You are right, humanity has never been known to be wrong for 300 years. Has sir Isaac Newton visited outer space perhaps to test the validity of his theories on classical mechanics ?
The topic of this thread is how thrust affects a rocket. The opening post was off off about all of this. We (or at least I) corrected him.
And right you did.
It should have been obvious to him that if he were right then all the rockets we've used to explore space would never have worked. The space shuttle wouldn't have been able to do all the things that we know that it did, we'd never have been able to send probes to Mars and most of the other planets in the solar system and we'd never have a Global Positioning System (GPS) that many people use nowadays.
These postulates are all part of my assumption.
The SCN presents all the major components of what can be defined as religion. Man lives among the gods (Jupiter, Pluto, etc.), human colonization of other planets will guide mankind to salvation, satellites will save us, etc.
Then we were insulted for our efforts with the claim that all cranks use, i.e. that we're all brain washed and can't think for ourselves, which is utter nonsense.
I thoroughly agree with your statement. You are among some of the brightest and most stimulating human beings on the planet, and true heirs to Thales of Militus.
Part of a physicists training is lab work where we experimentally explore what we learn in class. So we aren't merely told these things but are expected to observe them in the laboratory for ourselves.
PmbPhy , are you familiar with Aesop's fable The astronomer who fell in a well ?
The ending concludes as below :
"Hark ye, old fellow, why, in striving to pry into what is in heaven, do you not manage to see what is on earth ?"
To what empirical fact are you referring ?
Exactly what I was referring to, i.e. time and space have no affect on the pressure produced against the wall opposite the missing wall by the explosion. is an emperical fact. This doesn't happen.
To what laws of physics does this fact conform ?
All of them. Especially Newton's laws of physics.
My assumption, shared by others, is that man has never achieved flight beyond a hypothetical 80-120 Km altitude.
I see now. You're a conspiracy theorist who thinks that spaceflight to places outside that distance has never occured and that NASA and all the other space agencies on earth have lied to everyone on earth and everyon on earth bought it. Which means that hundreds of thousands of people in the world who work on it also lie and got away with it. And you're ignoring the fact that there are satelites in geosynchronous orbit around the planet which means that have to be at an altitude of 42,164 km.
http://en.wikipedia.org/wiki/Geosynchronous_orbit
Sorry but I won't talk to such people because I won't feed that kind of delusion past one post.
Three hundred years ? That is it ?
No. You need to read more closely to what people write. I said well over 300 years. I know it was fact of Newton's thinking and those that came before him. I'm not that much of a history buff so I don't know how far back it does.
You are right, humanity has never been known to be wrong for 300 years.
That's quite wrong. Newton's laws were found to be imprecise at atomic distances, at speeds close to the speed of light and in strong gravitational fields.
Has sir Isaac Newton visited outer space perhaps to test the validity of his theories on classical mechanics ?
One doesn't need to be outer space to know that it's true. In anycase Newton used data provided by Kepler about the orbits of the planets who determined the orbits from the observational data that Tycho Brahe collected. In any case all one has to do is get a rocket engine and place it in a vacuum to establish that it works. And we know that it works because for salelites to be in geosynchronous orbit they have to be at an altitude of 42,164 km. And we know there there because that's how satelite TV works. The dish must point in exactly the same direction all the time which proves the satelites are that high.
Thank you. That is very kind of you to say.
Let me explain what's wrong with your beliefs. They can't be applied to anything because if they are they fall apart. For example; if Newton's third law holds then its wrong to believe it only holds in an atmosphere. And if it didn't work in a vacuum then some smart experimentalist would have figured it out years ago, long before we put many in space. You can't think that NASA is that stupid, do you? If Newton's third law didn't work then we'd be unable to walk or drive a car because the facts that it refers to are in operation when you're walking or driving a car. You're beliefs focus on a very small set of facts and ignores countless millions of experiments done in laboratories all over the world where these things have been tested in every concievable way, including in vacuum.
What I'll never understand about people like yourself is why you think that so many hundreds of thousands of use physicists are so morally bankrupt and so corrupted to lie as much as you think they are. I've never met a scientist that evil. You certainly haven't done anything to justify your claim that no spacecraft has ever been higher than you claim, that's for sure. In fact you didn't provide any reason why so many people would all agree to tell the same batch of lies.
So that's all for me. I don't talk to conspiracy theorists, even if they try to provoke me by challanges or name calling. Sorry.
Post by: jccc on 28/06/2014 02:32:54
If he had the chance to fart in space, he'll believe us.
Quote from: jccc on 28/06/2014 02:32:54
Not in a spacesuit, he wouldn't.
In space no one can hear you fart - but sooner or later they'll know...
You are not helping him.
Post by: percepts on 01/07/2014 20:02:52
I haven't read all 5 pages so if its been answered...
Isn't the point that the high energy material whether it be gas, water or something else is pushing against the space craft as well as anything else it comes into contact with and in all directions. The thruster nozzle pointing in one direction causes the push in the other direction to be directly opposite to the nozzle direction. The motion is caused NOT by the high energy material pushing against what is outside the spacecraft but by it pushing against the spacecraft itself.
i.e. completely flawed assumption in postulation that thrust motion is caused by pushing against what is external to rocket engine.
Post by: Reality207 on 20/08/2014 03:46:01
I have read the objections to this statement and the arguments/logic behind it.
This subject has tormented me since childhood, as it does seem illogical that a rocket can work without resistance to push against.
Take the motorboat out of water and there is no resistance for it to push against.
Take the rocket out of atmosphere and there is no resistance for it to push against.
Ya sure Newton's law "what you push against pushes back", well if as in space there is nothing to push against or to push back, how can it be!!
I cannot explain why so many good scientists accept NASA's stories with such faith, but this is not a Conspiracy theory, it is logic. You must reach and live with your own conclusions. All I ask is that you don't blindly accept what you were forced to learn and accept and that you apply logic for yourself.
Further, I ask, as flight controls also require atmosphere to react against and there is no atmosphere in space, logic would also demand that flaps, ailerons, spoilers and elevators would not affect the flight path of a space ship in space as they all require atmosphere passing by them to function. Flight control - 101.
Now, realistically if we are to attain propulsion in outer space, logic demands it will have to be done by acting or reacting against something that exists in space. If we are to attain flight control in space it will also have to be done by acting or reacting to something that exist in space.
I'm sorry but again we don't have that at this time, and no explanation of how thrust works without atmospheric resistance is known or offered.
Sorry Please don't hate me for these thoughts, I share with all due respect.
Offer me a logical explanation of how thrust works without atmosphere to push against. Tell me how thrust can act or react without resistance.
Please don't sight the example of throwing a ball standing on a skateboard or while sitting in a chair on wheels, as both of these experiments are conducted in atmosphere.
Have you ever fired a rifle? The recoil force is exactly the same whether you fire it under water or in air. Recoil force is independent of the surrounding medium.
Conservation of momentum is demonstrated in many ways: billiard balls, "Newton's Cradle", spinning tops and skaters.... and in no case is there any requirement of "something to push against".
Rockets work by conservation of momentum, nothing else. You chuck stuff out of the back and the rocket moves forward so that the net change in momentum is zero.
Interestingly, motor boats and aeroplanes work on exactly the same principle, except that the "stuff they chuck out at the back" happens to be the same ambient water or air that they are floating in, accelerated by the propellor. The difference with a rocket is that you carry the stuff with you as there isn't any ambient stuff to use.
You may have noticed that true space rockets http://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&docid=xpmJJ5zcgCRSRM&tbnid=qpYSfLkBXvNeGM:&ved=0CAUQjRw&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FAriane_(rocket_family)&ei=hkn0U_mDM4TK0QWE7oC4Dg&bvm=bv.73231344,d.d2k&psig=AFQjCNHgZpahKRn9bUN56MEe01OpAWmX0A&ust=1408604919233069 don't have flaps, ailerons or even wings. Have you asked why not? Directional control in space is done by pointing the rocket motor the way you want to go. The fins on the archetypal V2, and on air-to-air missiles, are for directional control whilst the machine is flying in air, which it does for most of the time.
Ultimately you are going to have to convince yourself. Not difficult. You can buy a model rocket motor, attach it to a spring balance, and fire it in a vacuum jar. Or just watch what happens if you energise an electric bell or a newton's cradle inside a vacuum jar. The absence of air makes no difference to the conservation of momentum.
The problem you will have is accepting that the laws of physics apply equally everywhere. Fortunately for the rest of the universe in general, and pilots and engineers in particular, that seems to be true.
Post by: aasimz on 20/08/2014 18:56:46
If you will allow me I believe I have the perfect explanation for that, I think any layman should grasp.
Because a one can argue with the cubes and spring example saying that the surrounding atmosphere has to be considered as one of the cubes, and the spring being the force of the expanding gas.
Thrust in space actually depends on the fact that there is nothing to push against in space. How?
Well it's very simple, imagine a box in space with 5 sides, one at the top and 4 on the sides and the bottom is open, if we triggered fuel reaction inside at the center of the box the (360 degrees) pushing force of the expanding gas will push against the 4 sides equally so the box will not move sideways, and will push against the up side and move it upward, but there is zero push toward the bottom because there is nothing to push against there.
We have to bear in mind that the rocket in space will have zero gravitational mass meaning much less force can make a big effect, so if you have something to push against, there will be gravitational mass which will lead to consume a lot more fuel.
I can safely say you can use your deodorant to spin in space, because the gas release will make it push against your arm that is limiting it is expanding speed, it is the gas trying to spread equally in all directions.
Out of this, I believe space is definitely not empty, actually it is absolutely full, there is no single Planck scale space that is empty in the whole universe, it's not only me, but more than 50 research groups of physicists around the globe and more are working on the Loop quantum gravity (LQG), where the theory predicts that not just matter, but also space itself has an atomic structure.
First let me thank you for the gentlemanly reply, and the stimulating thoughts you provoked, in the words of my generation "groovy man".
Rifle, I see it differently, for the sake of discussion, lets use a custom built device that will fire under water, in space and in the atmosphere.
First lets fire it in the atmosphere, as the gasses expands the projectile will push and compress the air in front of it as it leaves the barrel. The gasses behind it will press against all side evenly, so the closed end, the barrel and the projectile will all see the same pressure. The projectile will see resistance from its contact with the inside of the barrel as well as the displacement and compression of the air in front of it until it leaves the barrel. As air compresses very easily the projectile will have no trouble exiting the barrel and will travel at a great speed until air resistance and gravity bring it to a stop. I'm sure we pretty much all agree on that.
Second we fire the same projectile under water, the barrel will be full of water that must be displace, as water cannot be compressed, it will be difficult for the projectile to leave the barrel. The projectile's velocity will be decreased almost exponentially. The projectile must displace the water in front of it that must displace the water in front if it and so on until the reaction reaches the end of the barrel. At this point the displaced water will displace the water above the end of the barrel toward surface (assuming you fired the device horizontally) that will displace the water above it and so on until the reaction reaches the surface where that water will disburse.
As we take the device deeper and deeper into the water a fire it again the displacement becomes greater as more water must be displaced upwardly and projectile velocity decreases prospectively. Eventually we will get deep enough that the resistance will becomes so great that the pressure of the expanding gasses will exceed the displacement rate and the barrel will explode.
The projectile will not travel very far in water, as the resistance from water that must be displaced all the way to surface is extremely high. Kick back will be greater as the pressure against the projectile is greater and velocity will decrease. The kick back will also last longer, push harder and further, as the projectile will take longer to exit the barrel.
Lastly lets fire the device in space, as there is no resistance to the projectile exiting the barrel, the only resistance it will see is the friction between the projectile itself and the barrel. The projectile velocity will be the greatest as the exit resistance is least. The only kick back force that will result will be from the friction of the projectile against the inside of the barrel which will be minimal and the resulting kick back will be almost non-existent. However the projectile will travel indefinitely, at the same velocity until it meets an object or other matter to influence its movement.
It's all very simple, and I am not a layman, but a student of all sciences and an independent logical thinker, I think.lol
I have to say that I must rethink my statement that, "the only way space travel will be accomplished is to act or react on something that exist in space." I do believe that the kick back in space with the rifle though extremely small and short lived could produce a miniscule amount of propulsion in space. If that kick back did occur in space it would do so without acting upon something that exists in space.
As the gun barrel has little to nothing in common with the rocket engine, which is to say that the rocket has no projectile to produce backpressure and thus propulsion, I have to maintain that I am not convinced sorry. No disrespect intended and I am very willing to listen.
The greatest number times zero is zero, the greatest thrusters against nothing (like in space) would seem to be zero and There is nothing to push against there how can there be a reaction?
Your Friend in science,
aasimz, Hi and thank you for your interesting response.
Someone a couple pages back added a diagram of two boxes and a spring in the middle between them both. I would like to use that; one box represents the space ship, the spring represents the propulsion and the other box represents the atmosphere. If we compress the spring and release it, both boxes will be accelerated equally provided both have the same mass and resistance.... but if we load the spring with only one box and release it, the box will not move, in atmosphere, in water or in space. This is how I see the rocket in space, it is as a single box and spring with no resistance to move it and no movement.
Or to use your example if you place two five sided boxes with the open ends toward each other and explode something inside them they will then both be accelerated in opposite directions by pushing against each other. This will prove true in atmosphere, water and space. In space they will each continue all the way to the moon or the Milky Way or what ever they may strike along the way and at the same speed they started at.
But as I see it and this is only my logic, with one 5 sided box and one explosion: in water or atmosphere there is resistance and resulting propulsion, but in space I don't see it, no resistance, no propulsion.
Clearly I would not have graduated your college programs, they would have hated me and found a reason to expel me.
By the way, clearly propulsion is space is possible without acting or reaction against something that exists in space, as the two boxes and the explosion proves, but the efficiency would be ridiculously poor. Space travel will become real when we find something that exist in space to act or react against.
I predict that when we do find that element or energy force.... we will blow away the speed of light and when we do that I further predict that we will cause a luminescent boom, the light equivalent of the sonic boom. Inverting light.
The only way I see us getting to the moon is if we fired a missile with enough momentum to leave our atmosphere, with the exact velocity and with the right timing (trial and error) so that a straight path would simple hit the moon. I'll bet that in less then five tries we could do it. To get back we would use current rocket technology but with the moon itself as resistance blast off on a straight path back to earth. That would be tricky as the only method of hitting the earth would be to use the exact amount of thrust against the moon to accelerate the rocket to a speed that would cause it's timing and velocity to hit the earth.
we would only have a short distance to accelerate against the moon as there probably is no atmosphere there I don't know, but it wouldn't take much as there is no resistance holding it back.
Ok, I will try to elaborate more on how we don't need an atmosphere to push against.
When you think about it, the gas will expand rapidly from a single point at the centre of the box, when the first atoms reach the sides of the box they are pushed by the atoms behind them and forced to push into the sides, you can consider the centre point as an anchored point in space as the sparks continues. so, it is the gas pushing against it self, if the fuel reaction generated enough force it will explode the box in order to spread in all directions equally, even if one of the sides was open.
The gas will expand the same no matter where it was in the universe.
As for your concerns about the efficiency, well it is not poor as you think at all, considering the gravitation pull at the opposite direction, just like earlier mentioned the amount of the fuel used only to get out from earth atmosphere is much more than the amount used to travel much greater distances out of gravitational fields and out of atmosphere.
If a dynamite explosion took place in space beside you, aren't you going to be effected by this explosion, yes and you will be effected more -by the same dynamite force- than if you were in earth, it will be a stronger effect and you will gain more acceleration than in earth with the same propulsion force, because there is no gravitational mass, and there is no resistance against you, and no atmospheric resistance against the expanding gas. The dynamite explosion will generate the same force always anywhere.
Quote from: Reality207 on 21/08/2014 02:13:51
As far as the physics is concerned, they are identical. The rocket's "projectile" is the exhaust gas molecules.
I do believe that the kick back in space with the rifle though extremely small and short lived could produce a miniscule amount of propulsion in space.
Alas, belief has no place in science. Nor do words like "extremely" and "minuscule" - physics is about numbers, not adjectives. Conservation of momentum, however, seems to apply throughout the observable universe, and the numbers add up with sufficient accuracy to allow us to walk, fly, and travel to the planets.
alancalverd - Again thank you for your scientific response.
I agree that the potential energy/force of an explosion/fuel will always be the same; simply put "it is what it is". But I ask respectfully; doesn't the resulting action or reaction totally depend on the environment?
Being 20 feet from an exploded stick of dynamite in atmosphere would hurt.
Everything between one and the explosion would strike one and likely cause one to be knocked over while being "peppered" with the material wrapped around the dynamite and all the material in the atmosphere. As atmosphere is easily compressed one would have area to be trusted into, resulting in minimal damage.
Being 20 feet from an exploded stick of dynamite in water would be fatal.
Everything between one and the explosion would be trusted toward one but as water cannot be compressed one would have nowhere to go and would be crushed by the pressure of the expansion.
Being 20 feet from an exploded stick of dynamite in space??
Everything between one and the explosion again would be trusted towards one, as there is nothing (we know of) in space, one would only be hit by the wrapping of the dynamite and the particles of the dynamite itself, resulting in the least amount of damage. As an object in motion tends to stay in motion…. And energy cannot be created or destroyed only transformed the flying particles striking one would cause one to be acted upon, resulting in movement or thrust in space. The result is that one would be hurled endlessly across the universe at the same speed one was accelerated to.
You are gaining in convincing me; however many elements still remain in question.
Sorry time has come that I must depart; please, I will return and I dearly look forward your thoughts.
Why would you worry about injury or the material that was wrapping the dynamite and other details, forget all that, we are talking about the force that has been unleashed.
Underwater, as a result of water resistance you will get the least momentum out of that force. Through air a greater momentum. In space it will be the greatest of all, not only because there is no atmospheric resistance but also the non-presence of gravitational effect.
First, you must learn the meaning of the technical words you use. Energy, force, momentum and power are all quite different things and whilst you use terms like "energy/force" you will not be thinking clearly enough to follow the physics.
I suggest you learn the definition of momentum and the principle of conservation of momentum before continuing this discussion. Indeed once you have done so, you will immediately see why rockets work in space!
A great deal of the public misunderstanding of science is due to the imprecise use of language.
In the case of a rocket engine, the engine is the environment.
Post by: jeffreyH on 22/08/2014 21:06:35
What is pushing are the energetic particles of fuel that are expanding in all directions. I have only read the last page of this thread but find it reasonable that people have problems with this. We think of a push as having to have two elements simply because we as humans have to brace against something to push. If you were to throw 1000 rocks simultaneously at object it will move. The rocks have left the hands before they start to move the object so where is the push backwards? It is the recoil of the rocks from the surface of the object being moved as per Newton.
I cut and pasted from alencalvard's thread
"Have you ever fired a rifle? The recoil force is exactly the same whether you fire it under water or in air. Recoil force is independent of the surrounding medium."
I couldn't disagree more Sir ( I hope I am allowed to do that without angering you or anyone else)
Maybe we are having a language break down?? Please correct the science, not the language.
I see the environment has everything to do with the reaction or kick back.
The potential force does not change in different environments! but the result has to change in different environments, as part of the result has to be influenced by the environment.
Gun powder is gun power in any environment and it's potential will be the same I agree (potential f=ma) but resulting force or kick back when it's energy is released will never be the same in different environment. Everything it touches or that touches it will effect it and if nothing touches it nothing will affect it.
I realize this may upset many but kick back = ma/r r being the environment which is the resistance. The resistance of water is much different then the resistance of air.
Run through water then run through air, your potential MA doesn't change but everyting does.
"what you push against must push back" push against water then push against air, air will compress and not push back much, water does not compress and will push back alot. push against space and nothing pushes back as there is not (I don't know what I'm missing here??)
I have written lenghty explinations of this that can easily be done here on earth, here's another.
A rifle with a completely sawed off barrel, fired in water, with no projectile, will still have a great amount of resistance as the gasses will try to press into the water that cannot be compressed causing a pill up of the gass, back pressure and a considerable kick back.
A rifle with a completely sawed off barrel, fired in air, with no projectile, will have almost no resistance as air compresses very easily, there is almost no pill up and almost no back pressure and the kick back will be almost nothing. KB =MA/R. KB = kick back
thus environment changes forces in action or the kick back, How can you not agree !!!! ?
Maybe we are having a language problem here so please try to understand the thoughts, as perhaps I don't speak your language hopefully you can speak mine.
The dynamic of every atom, every molicule.... has to change when the environmet is changed, as the action and reaction of each one of them is effected differently in different environments. Come on, seriously!!!!
A rifle with a completely sawed off barrel, fired in space, with no projectile, will have no resistance at all and the rifle cannot have any kick back at all, as there is nothing there to act against it.
"Everything you push against must push back", does not and can not apply, as when you push against nothing the law becomes invalid. sorry but .... think about it!!! 0 x 10K = 0
This third scenario to me would most seem to resemble the rocket engine and why I must still conclude that it should have no thrust in space.
I hope I am allowed to have and share my thoughts and opinions, logic and views, even if they are different. I intend NO DISRESPECT to anyone!!!! These are simply my views.
Alen, if you are still reading this. sorry I was away, unavoidable; would you please explain what you intend when you wrote, "the engine is the environment"?
It seems we are going round and round, but if anyone is willing to explain where the resistance comes from or why it is not needed, I am willing to listen.
Question – what do we know of that actually exists in space? Like radiation, gravity….?
On a different subject, as this is getting old...
It is my understanding that the current belief is that, water displaced from the front of a submarine is pushed to the back of the submarine. There was an experiment where they ejected ink from the front of a submarine and watched as the submarine moved through the ink and the ink fell in behind the submarine.
Is this the general consensus?
Because I have an interesting experiment to share on that, if anyone is interested?
"It is the blend of science and art that leads us to creativity and progress." rl
aasimz wrote
"The gas will expand the same no matter where it was in the universe."
The gas will have the same potential to expand anywhere in the universe. But as everything it touches and that touches it during expansion, in different environments, will be different, the resulting reaction will be different, everywhere, and so the expansion has to be different!
Contain expanding gas in a rigid box then , then contain the same expanding gas in a balloon
two very different reactions will accure. am I missing someting in what you are saying in the above quote?
The environment will always affect the action and the reaction.
aaismz wrote
We must be having a language thing as that is exactly what I have said, except you correctly add gravity.
My question remains, "how the thrust occurs in space that results in that momentum"?
aasimz also wrote,
that is all true, but again if the first of the expanding gas doesn't strike anything, like in space where there is nothing push back against it continues indefinately and the explination would seem to become invalid.
Sorry I am not trying to be combative, only logical. Perhaps I am missing something?
Jeff wrote,
"If you were to throw 1000 rocks simultaneously at object it will move. The rocks have left the hands before they start to move the object so where is the push backwards? It is the recoil of the rocks from the surobjeface of the object being moved as per Newton."
In your analogy the hand represents the rocket and the rock represents the out gas or expanding gasses if I understand your analogy.
In space there is no object for the thrown rocks to strike, so the thrown rock will continue indefinately, there is no recoil, and the hand will see no return thrust; just like I see the rocket in space, no thrust.
Im sorry if my view seem to be anything but respectful, I am not intending to be argumentitive but this analogy doesn't work for me.
Thank you for your understanding of my questions. and thank you for your attemp the help me understand this, but I still don't understand it.
In your analogy the hand represents the rocket and the rock represents the out gas or expanding gasses
No the hand is what releases the gas, and the rocks are the gas particles and the object is the rocket. And the recoil happens for the gas particles exactly as for rocks and according to Newton's law.
Back to front reasoning.
Start with a rocket in space, not moving. The total momentum of rocket (mass M) plus fuel (mass m) is zero. Now expel the fuel as exhaust gas at velocity v. Since the total momentum must be conserved, mv = -Mv' where /v'/ is the speed of the rocket. The minus sign is there because v and v' are vectors with opposite directions.
If the initial potential energy of the fuel was E than E = (mv2 +Mv'2)/2, from which you can work out the final speed of the rocket - at least in principle: reality is a bit more complicated* because the mass of the rocket plus residual fuel is changing throughout the burn, and some of E is lost heating the rocket engine, but you get the general idea.
Thrust is the result of conservation of momentum - nothing more or less.
*rocket science is dead easy - in fact it's all in these two equations - but rocket engineering is a lot more difficult!
1. if the hand is what releases the gas it is part of the rocket, how can it be the acting and the acted at the same time?
2. How does the recoil happen from the gas particles? are they not all traveling at the same speed?
Again it is really great that you take the time to try to explain this, Thank you, all.
E is obvious, M and m are obvious, but the equation doesn't explain how in the physical world, the rocket attains V? Equations, formulas and theories are not going to convince me.
If rockets work in space, (and I'm not saying they do or don't, just that I don't see how), it could be explained using actual parts and product, their actions and reactions, by and to particles and substances. Couldn't it??
Momentum is conserved, anywhere and everywhere. Why not in space? Given that, and the definition of momentum (mass x velocity), if we start with M and m stationary and not connected to anything else, then give an impulse to m so that it attains a velocity v, conservation demands that M must move in the opposite direction with velocity -v' such that mv = -Mv'.
You can apply the principle to rocks, particles, cricket balls, planets, anything you fancy. The force pushing the gas out of the back of the rocket produces a reaction force that accelerates the rocket in the opposite direction (Newton). Actual particles and substances used in space travel include steam, oxides of nitrogen, mercury ions, and a whole lot of more exotic molecules depending on the particular job to be done.
Alan wrote, "then give an impulse to m so that it attains a velocity v,"
I understand all that and I agree except for that one little part, I seem to be hung up on again or still, how is the impulse provided, where does V come from??
Before momentium is conserved, it must be stablished or its just potential, right?
Do submarines interest you?
I have a propulsion system that will put submarines over a hundred miles an hour. EASILY
G-Force that will cause one to pass out, move through water like it was air.
On everything that I am, everything that I have, I guarentee it!
Something like that worth anything $$, to whom? and how would one, "cash it in"?
The hand most definitely does not represent the rocket. The hand represents the centre of the explosive release of the gases. The rocket is to be considered a separate system entirely from the ignited gases otherwise you are bootstrapping a system under its own power which is nonsense. The expanding gases push EVERYTHING away from them including the rocket. That is why there is an outlet for the gases AT THE BACK.
The impulse comes from burning fuel. This converts the potential energy of the mass m of fuel into kinetic energy = mv2/2, hence we have m and v, thus the rocket moves at v' so that Mv' balances mv.
Sorry, this is meaningless. Momentum is always conserved. You must appreciate the difference between ∂ mv = 0 (the sum of momentum vectors doesn't change) and ∂ mv2/2 > 0 (kinetic energy is created from potential energy). Note that v is a vector but v2 is a scalar, which is what it's all about!
only as targets.
I think you would need to improve your grasp of elementary physics before presenting it to a potential customer.
An ice rink is a good place to get an understanding of these concepts because of the low friction. If you are standing still holding another person and you push them away, they will move away in one direction and you will move in the opposite direction. If you're holding a shopping trolley full of rocks and start throwing them away, one by one, in the same direction, you will get a small impetus in the opposite direction for each rock you throw. The more rocks you throw, the faster you will go. The rocks don't have to hit anything. If you use a fire extinguisher, the gas coming out has the same effect as throwing thousands of tiny rocks - you'll also get an impetus in the opposite direction. In a vacuum it will be even more noticeable because of the lack of air resistance to your motion. That's how a rocket works too. Newton's Third Law.
Quote from: Reality207
Hi Reality207,
I see that you're back trying to prove that all of NASA and every single physicist who's alive today is wrong, huh?
What you said here is, again, not true at all. In fact all one has to do to demonstrate this oneself is to obtain a skateboard and a heavy stone. Sit down on the skate board and make sure its on a very flat smooth surface. Make sure that you and the skateboard are at rest before you throw the stone. Then throw the stone as hard as you possibly can parallel to the ground. The exact moment the rock leaves your hands the whole system of thrower + skateboard will recoil. You and skateboard won't wait until the rock see if there's something to hit because the rock and skateboard doesn't think. And we can replace you with a strong spring and a remote control.
You see, physicists are pretty darn smart people. When they make a law the first thing they do before stating that something is true is to actually see if it is experimentally first before they make claims. Not one of us is so dumb as to postulate a law with nothing to base it on. Physics students do these experiments in their very first year of study when they start their training in college to get their degree in physics. I'm sure they do the same in high school but it's been so long since I was in high school that I forgot.
I've been reviewing your posts in this thread and one of the things that I've noticed is that you're confusing two kinds of propulsion systems; there are those systems that work by pushing against a medium, such as airplanes and boats, and those that work by Newton's Third Law like rockets and missiles.
Here's a simple way to prove it too. Obtain a vacuum pump which will allow you to pull down a decent vacuum. Then get a large long tube or container which is see-through so that you can watch what's going on inside. Get another very very long PCV pipe and attach the other end to a very large container. This PCV pipe and container will allow the exhaust to be moved away for a few seconds so that you can watch the rocket move. Then get a rocket engine from a place which sells model rockets. Learn how to use them so you don't burn yourself or hurt yourself. With these materials you can construct your own vacuum chamber and watch how right NASA and the rest of us are.
I'm still curious as to how you think Men put corner reflecting mirrors on the Moon or satellites in geosynchronous orbit. Would you care to explain that for us?
first Thank you for your kind responce.
Now your analogy is completely bogus, as there is something foolish people like me call ATMOSPHERE to resist the ball and allow it to accelerate the person on the skateboard that DOES NOT EXIST IN SPACE.
This evening I read for the first time about EmDrive, this is logical to me foolish as I may seem to you. but no one and that includes you Sir has presented ONE element of logic that explains how rockets can thrust against nothing.
let me look through your big telescope and see the flag, the rovers, the mirror I never hear of.
I have a serious question
I went to the space musium and looked at the lander, and the rover, where did they put the rover to carry it up there? How did they attach it? no one at the musium could answer that question, will you?
I'm not saying we didn't go there I'm saying I don't see how, so please do be mean to me as these are fair and reasonable questions.
I'm not trying to offend you, can you say that?
Now your analogy is completely bogus,
That's a rude way to express your thought.
as there is something foolish people like me call ATMOSPHERE to resist the ball and allow it to accelerate the person on the skateboard that DOES NOT EXIST IN SPACE.
Not at all. You totally missed the whole point of the experiment. This was about momentum and you treated it as if it had to do with an interaction with the atmosphere. That's easily proven to be total nonsense. Your assumption means that the ball is acting with the atmosphere and it has nothing to do with momentum. That'd mean that the recoil would be independent of the mass of the ball which is empirically incorrect as experiment demonstrates. The larger the ball the more resistance to air. You can keep the mass the same and adjust the size and that will change how the throwing affects what happens. The idea is to make sure that the stone is so small that atmospheric forces can be ignored. That's why you needed to go to take physics classes, i.e. so you wouldn't keep making such horrible mistakes like this in every single post.
The problem is not with us. The problem is with you. You lack the ability to understand the physics. That's all there is to it. Sometimes that happens but none of them are able to admit it. Your claims are all contrary to both theory and experiment. Countless experiments have been done which you know nothing about which prove that you're wrong a thousand times over. It's not up to us to convince you that the science of physics is wrong. It's up to you to learn it before you can make any judgments about it. So do what so many of us physicists have done and spend a half dozen years in intense study learning why physicists hold to be true what we do. Then you have the right to claim everyone in the world is wrong and you're right.
So! Once again I see that you failed to answer my questions and then expected me to answer yours. That's never going to happen. If you can't be respectful enough to answer a question given to you and you rudely ignore it then there's no way in hell that I'll address yours.
I am preparing my answers, I have been since that last post, not ignoring anyone
I will post it when I complete it and I am doing so.
in fact I was about to post when I read your second past and changed my reply.
Sorry guys if I let my emotions effect me there, pmbphy is not patient like you other
Gentleman, I noticed that in some of his other response. And I hope I didn't say anything to offend you guys, as you really have been very kind and patient trying to explain this to me. But the analogies on earth with atmosphere just don't help me understand, as there is no atmosphere in space. You sit on a chair; the chair pushes back. Take away the chair; and there is no push back. Everyone keeps saying Newton's law I totally agree but how does it apply if there is nothing to push back? I guess I can understand why I probably up set pmbphy, but that is not my intention. I'm NOT a conspiracy theorist and I'm not trying to prove anything, sorry if I seem that way.
Sorry pmbphy I let my emotions get to me.
Pmbphy I am a master electrician not a physicist, that's clear. But I have a customer that bought a house wired by a physicist and I fix his electrical work all the time, I don't have the heart to tell the customer to rewire the whole house or how much his work scares me. So please, I ask you not to be so condescending and mean. I believe I have the right to ask these questions without getting this attitude. And I don't care how much you spent on education, that doesn't give you the right to insult people who don't agree with you.
Jeff and Alan wrote something's I'm going to reread study that I have not absorbed yet and would like to. Well try anyway lol. I am also going to try to understand what Pmbphy wrote between the insults.
Alan, I still have emails from ONR where I explained to them about a plow shaped nose tip modification, that would reflect/displace water more efficiently upward, allowing greater speed sighting that displacing water downward is not as easy as displacing it upwards. and found out recently they are now experimenting on something just like it. You know what I am implying. But I must be wrong and they must have had it before me. haha
And I take no offence to your answer about my lack of physics, as I know you wouldn't do that. Thanks,
EmDrive the future of space travel, love it. I'm an electrician you can probably understand why.
Perhaps I should say,
Your student in science LOL
Reality207 - Let's start from scratch such as the treatment in Classical Mechanics by John R. Taylor which you can download at http://bookzz.org/book/911552/5131aa
Turn to page 85. That's the page where the section entitle 3.2 Rockets starts. It goes from page 85 to page 87. Please study that section and get back to us.
pmbPhy I will do that.
I am happy to do that.
ps I was going to me this my last post, I will get back to you.
Sorry guys if I let my emotions effect me there, pmbphy is not patient like you other Gentleman, I noticed that in some of his other response.
I was upset when I saw you write this. You hardly know me so you have no cause to make such a claim such as this. You might have said something like Pmbphy was being impatient since that shows a particular state of mind whereas pmbphy is not patient says something about a person's character which takes a while to learn because you have to get to know them.
Everyone keeps saying Newton's law I totally agree but how does it apply if there is nothing to push back?
That is quite correct. It's what led Einstein to general relativity.
Einstein to his the- I guess I can understand why I probably up set pmbphy, but that is not my intention.
No problem. I'm finally getting to understand you better now. You could be a great deal more intelligent than I thought you were not that I've gone back to studying your posts. :)
Pmbphy I am a master electrician not a physicist, that's clear.
This is something we have in common. I started off as an electronics technician and saw that I was capable of doing a hell of a great real more. So I stopped being an electronics technician and went to college, learned math and even though I totally sucked at arithmetic I was wonderful at trigonometry, algebra, geometry, calculus, etc. It's a good thing I wasn't married since that would have been a problem.
I am also going to try to understand what Pmbphy wrote between the insults.
Thank you. I'll try to do the same with you too. Think what happened was that you and a lot of people do, i.e. they confuse negative criticism with insults. Have you ever noticed that yourself?
That's Wonderful my new friend. I see that we're good to go on this then. Great! [;D]
Maybe there is no hope for me [:-'(]
I read John Taylor and he wrote –
Consider the rocket shown in Figure 3.2 with mass m, traveling in the positive x direction (so I can abbreviate vx as just v) and ejecting spent fuel at the exhaust speed
vex relative to the rocket. Since the rocket is ejecting mass, the rocket's mass m is
steadily decreasing. At time t, the momentum is P(t) = my. A short time later at
t dt, the rocket's mass is (m + dm), where dm is negative, and its momentum is
(m + dm)(v dv). The fuel ejected in the time dt has mass (—dm) and velocity
All I get is, "the rocket is lighter because of repelling fuel and being lighter will allow it to go faster." Sorry, Am I missing something?
Also, I don't understand or he didn't include, how the rocket in his explanation got moving in the first place?
John Taylor wrote - "when you push one way on the boot, the boot pushes in the opposite direction on you." I don't understand that, sorry (and I almost want to tremble to say this) I don't see just the boot pushing as JT states. The boot and the arm in motion push against the atmosphere and the atmosphere pushes back against the boot and the arm. Doesn't it??
Aren't the atmosphere, the boot, and the hand in motion are an example of Conservation of Motion all acting together?
How come JT doesn't mention atmosphere? It must be me???
I hope this is not inappropriate both personally and to the host, but I am going to take a chance (I probably can't sound crazier then I do) and make a Proposition.
I have a feeling you guys PmbPhy, Alan, Jeff, and Dlorde know people with real money, maybe even yourselves.?
I really do have a submarine hull design that will go over a hundred mph do spins, flips, like a roller coater... move through water like a knife in soft butter.
I know how crazy this must sound but I also have a sub design that will do over a thousand mph. However like a dragster, it will not steer well, its speed will only be limited by HP.
I have a design for the fastest aircraft hull. It will go as fast as any propulsion system will take it, in our atmosphere, No more nose tip resistance! Look at me the guy who's always talking about atmosphere, haha.
I am willing to put everything I own, "put my money where my mouth is."
If you guys can get me/us in front of an investor(s) we can trust.
Terms to protect everyone:
1. we agree on a price for each and terms:
2. the money, my assets and terms go into a closing company:
3. you bring existing designs to protect me, but don't show me:
4. I share my new design, we go over them.... and they work or I loose.
5. if my designs already exist (they don't or they would be using them) - show me the designs exit, and I loose. There is no exposure showing me, as I already know the design.
6. we build them, share the money.
Nothing to loose (x-time) and everything to gain.
Or we can figure something out and let Alan make the presentations.
Or tell me if there is a better way, I will share it with you.
I don't have a lot of time left in my life, I'm laying it out, I have a daughter in college with student loans..... enough said.
Post by: RD on 27/08/2014 10:09:50
... I know how crazy this must sound but I also have a sub design that will do over a thousand mph.
[hydrodynamic] drag is proportional to the square of the velocity ... http://en.wikipedia.org/wiki/Drag_equation
i.e. to double the speed you have to quadruple the engine power.
Current submarines can do 40 mph submerged, so to do 1000 mph the engine would have to be 625x more powerful , 625x bigger , ( that's more engine than sub) , with 625x current fuel consumption.
So a 1000mph sub is unfeasible.
If you're thinking of using bubbles to reduce hull drag, someone has beat you to it ...
http://en.wikipedia.org/wiki/Supercavitation
http://www.marineinsight.com/marine/marine-news/headline/how-air-lubrication-system-for-ships-work/
Do you have a patent on your designs? If you have, we can discuss them openly. If not, they are of no interest to an investor.
Be aware that patent examiners do know a lot about classical physics. There was this young lad in the Swiss patent office called Albert Onestone or something...
You couldn't have been more wrong.
So? Contact the Navy and talk to them.
I know how crazy this must sound ..
Very much so. Especially I see no way to believe that you already built a life size mockup.
but I also have a sub design that will do over a thousand mph.
How do you know that? From what I've seen so far of your understanding of physics you don't have the ability to design such a hull or predict the performance of a hull design.
More on your efforts to claim why Taylor's section on Rockets. I wanted to correct something in your post so that you might hopefully correct fully it before the next time you post. It has to do with notation. You wrote
Since the rocket is ejecting mass, the rocket's mass m is steadily decreasing. At time t, the momentum is P(t) = my. A short time later at t dt, the rocket's mass is (m + dm), where dm is negative, and its momentum is (m + dm)(v dv). The fuel ejected in the time dt has mass (—dm) and velocity.
where it should have been written as
Since the rocket is ejecting mass, the rocket's mass m is steadily decreasing. At time t, the momentum is P(t) = mv. A short time later at t + dt, the rocket's mass is (m + dm), where dm is negative, and its momentum is (m + dm)(v dv). The fuel ejected in the time dt has mass (—dm) and velocity.
It might caused you problems now or later.
Tell me. Have you ever considered what would happen if to massive objects were separated by a compressed spring and the spring was let to expand? What would happen?
http://home.bt.com/techgadgets/technews/supersonic-submarine-could-cross-atlantic-in-an-hour-11363928949889
Post by: Ethos_ on 28/08/2014 02:18:35
If you can't understand the following thought experiment, then I'd say there is no hope for you, but alas, I'll give it a try.
Imagine an explosion inside a rocket somewhere out in space. What will happen? The rocket will disintegrate into pieces all traveling away from the origin of blast. If the rocket is symmetrical in design, a sphere, the fragments will depart in a fairly evenly distributed pattern. Now, let's put a nozzle at any point on this object and repeat the experiment. If the structure of the sphere is strong enough, the blast will propel the single object in the opposite direction of the exhaust from the nozzle. And even if the sphere is not strong enough to withstand the blast, the majority of the fragments will still travel in opposite direction of the nozzle.
If you can't understand this simple principle, there is absolutely no hope.
Has anyone ever tired taking a fast jet as high as it can go and at a speed of 300 mph do a dive and accelerate slowly then at 725mph shut the engine off just before passing out haha and crossing the sound barrier in silence?
I know! But?
What if you equiped the engine with a rotation resister that would allow it to start slowly and dissipate the sound over a great distance, all you would then have to do is accelerate enough to attain positive propulsion before re-crossing the barrier and go zoom with acceptable boom? HaHa,HaHaHaHa
You sure you don't want to see my design?
The "sound barrier" has nothing to do with the engine. You can see the compression shock wave from a supersonic bullet, a freefalling ballistic missile, or a bomb that exploded a few seconds ago, and you can hear it from the free-spinning propellor of a plane in a steep dive with the engine off.
Happy to look at your designs if they are protected by patent.
happy to do so
can you private message me
provisional patent OK
I changed my mind Alan, and it seems you did too? [:-'(].
Patents become public and as there are companies that monitor the patent office with the intent of Circumnavigating patents, so as to steal the invention, I'm not willing to chance that.
Furthere there are too many nations that do not acknowledge U.S. or Internations patents.
After what I perceive as a fair and reasonable investigation into rocket propulsion in space; with what would seem to be top rocket scientist, engineers and physicists in the industry; and after having read the related pages from a number One best selling book on the subject and having invalidated all the attempts to defendable and/or explain the actual mechanics of how rockets thrust in space, I have no choice but to conclude that the irrational, that should seems inconceivable, is invariably the truth.
There is, at this time, no valid evidence, presented to me, that rockets work in space.
I am still willing to hear any sound, mechanical, explanation of how they work. And admit if I am wrong.
I am not willing to listen to the invalid applications and analogies of Newtons Laws of Motions. As I am tired of explaining that One Can Not Push Against Something That Doesn't Exist. "Realities Law."
Is it really so unconceivable that this could be a hoax!
Let me be clear on this, I do NOT fault the scientists that design these rockets, the people that assemble them, or the people that serve in any way. How do any of them truly know what happens after it launches and leaves our sight?
We are a nation full of hoaxies, for example; oil companies profit HUNDREDS OF BILLIONS of dollars a quarter EACH !!!!!! while our parents, friends, our sick and elderly who raised us, who built our schools, our homes and our nation, have to choose, in their age and time of need, rather to buy oil, food or medicine they need to stay alive. SHAME ON ALL OF US, ME INCLUDED. And I am deeply ashamed.
To me; this is not just one example of how we as a nation allow these hoaxes, but an example of the sicknesses that we all share, not just the immoral, sociopathic, greed driven maniac owners/boards of the oil companies, but us, as we stand by idly and ignore it or worse we buy stock in them laughing it off saying, "if you can't beat them join them".
[:-\]
..and having invalidated all the attempts to defendable and/or explain the actual mechanics of how rockets thrust in space, ..
You've never done any such thing. You've only deluded yourself into believing what you chose to believe from the start. We've proven it to you time and time again. I gave you the proof from Taylor's text and you didn't understand it. All one needs to understand is Newton's third law which is easily demonstrated. Look it up on the internet.
I've constantly asked you questions which you've refused to answer, i.e. how did they put satellites in geosynchronous orbit? How did they put the GPS satellites in orbit? How did astronauts get to the moon in while there place corner reflectors on the surface http://en.wikipedia.org/wiki/Corner_reflector. What is it you thought you were watching from all the television signals coming from the space shuttle in the early years? How did Google get satellite images of Area 51, etc, etc, etc,
Something tells me that if we were to place you in a rocket and send you to the moon, you'd return to earth still convinced that rockets don't work in space. Like you've previously said, "hopeless"..............................
Quote from: Ethos_ on 30/08/2014 15:44:03
Something tells me that if we were place you in a rocket and send you to the moon, you'd return to earth still convinced that rockets don't work in space. Like you've previously said, "hopeless"..............................
You've hit the nail right smack on the head. We'd be accused of drugging him or something.
Standard "mad inventor" response, I'm afraid. The problem is that if you don't have patent cover, you will accuse me of leaking your designs to your competitors.
Have you noticed how many people get their TV service from a parabolic dish pointing upwards? Have you noticed how, as you travel towards the equator, these dishes point more vertically? Are we all suffering from mass hypnosis, or is there something up there sending TV signals to earth? If so, how did it get there?
OK, let's suppose that geosynchronous satellites are launched ballistically (i.e. from a bigger gun than anyone has ever made, but in secret, and from several countries, and the pathetic little UHF repeaters you have seen are just a joke - the real ones can withstand a 1000 g launch). But you do seem to have accepted that some humans and other bits of stuff have been launched by this mysterious nonrocket. And you may believe that some of them (indeed most of the humans) have been recovered from orbit. Now how did they do that? A long piece of string attached to the International Space Station? Or just maybe some kind of motor that works when there is "nothing to push against".
Money talks. If I had bought a zillion-dollar satellite and it just disappeared over the hill when t he rocket fired, I wouldn't commission another one. But many very clever investors and generals have comissioned many satellites for all sorts of purposes, and seem quite satisfied to keep spending money on rocket launchers.
Or perhaps you might be interested in a personal point of view? I fly out of sight of anyone, several times a week. But I keep in touch with mere mortals by radio, and they watch me with radar, so we all know exactly where I (and several others) am. Curiously, I find that my GPS system, which can only receive signals from above, tells me pretty much the same thing as my maps, calculations and radar traces, so I'm inclined to believe that there are transmitters way up in space, put there either by magic or rockets. I can't think of any reason why the laws of electromagnetic wave propagation which apply to my piston-engined aeroplane shouldn't apply to my astronaut friends' Soyuz rocket. Perhaps you can?
They folded it up and put it in a space on the side of the lander.
Google is your friend (http://en.wikipedia.org/wiki/Lunar_Roving_Vehicle#Deployment).
The NASA web site has full details and schematics.
http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_lrv.html
http://historicspacecraft.com/Lunar_Module.html
http://www.collectspace.com/ubb/Forum29/HTML/000731.html
http://www.armaghplanet.com/blog/nasas-lunar-rover-everything-you-need-to-know.html
It no longer surprises me that we get treated like front-ends for Google. The most sophisticated search engines ever developed have put almost all knowledge at our fingertips, but some people still want someone else to do the work for them...
True. Back to the endless proofs that we've give him
http://www.nasa.gov/audience/foreducators/rocketry/home/what-is-a-rocket-k4.html#.VBBJOvl_vK8
http://www.thescienceforum.com/physics/46137-how-does-rocket-engine-make-ship-go-forward.html
http://en.wikipedia.org/wiki/Rocket_engine
Quote from: SteinUntStein on 20/01/2015 14:32:16
I have read this entire thread and joined this board specifically to revive this topic.
In summary/prelude, I want to say I agree 100% with what Truthseeker67 has been arguing.
All that proves is; That neither Truthseeker67 nor yourself understands physical science enough to grasp Action and Reaction. And if you don't like the answers gathered at this forum, try searching out your disagreements on Wikipedia. Then, if you don't like those answers, start your own forum..................Enough said!
Quote from: SteinUntStein
You're claiming to have carefully read all 160 replies?
Then you haven't read what the arguments presented to him carefully enough. We explained to him the fact that thrust needs to atmosphere to work in and provided multiple examples. We explained all of this more than adequately and in detail. He was simply unable to understand what he read. We explained to him that rockets work on the principle of Newton's third law, which he essentially claims is wrong, even though there is more than ample experimental evidence to the contrary.
The example I myself gave to him is the fact that in order for the space shuttle to achieve orbit the thrust of the rocket's engine must work in the absence of an atmosphere. Otherwise it wouldn't work. When the space shuttle wants to return to earth it must ignite the engines so that the thrust will slow it down enough to enter the earth's atmosphere.
Excellent! Perhaps you will enlighten us, then, as to where satellite TV and GPS signals come from, how some of my friends got into and out of various orbiting machines (some of which you can still see in the night sky), and why communications companies and the military continue to spend zillions of dollars on things that don't work.
Or just start by explaining where Newton, Whittle, von Braun et al went wrong.
Theoretical science is the new religion. Its disbelievers, heretics.
Wrong. Heresy is the essence of science.
I couldn't have said it better myself! :)
Post by: SteinUntStein on 22/01/2015 21:37:14
I'm not here to make enemies. I am trying to be upfront. I have been greeted with anything but cordiality.
It is confirmation about the way Truthseeker seemed to me to be treated.
The fact that some of you want to know about me rather than discuss the issues is indicative of the deeper problem.
As I say, I intend to insult no one personally, but such treatment as was given Truthseeker is unacceptable in any forum.
This is my issue. Throughout your debates with Truthseeker very few responses answered his very good questions and points.
No, most responses took the form of "because we say so and if you don't believe it you are stupid."
I understand some impatience, and I understand having to deliver a little scolding once in a while. But man, I say he was bullied.
For the record, I have yet to see any proof (I have heard some of the science) that thrust works in space, that is, in an alleged vacuum, and none here as convinced me.
I am NOT an expert in this field although I can drop names with the best of them and make you think so. But seems to me action=reaction is not applicable in space, and several Earth-based experiments in a vacuum seem to confirm this.
It's not really, for me, whether he is or I am right or wrong on this issue. Not primarily. First it is this authoritarian attitude with which he is answered.
Only confirms to me that people guided by today's theoretical science are worshiping a religion. Same commitment, same lack of proofs for fundamental premises, same excommunication recommended for anyone who does not believe, same smug surety in what most of them have never witnessed, in this case, thrust in outer space vacuum.
Science, by my understanding, is both practical and theoretical. Practical science gives us things we can use, pragmatic tools for living, technological advancement. Theory on its own can be held by any lunatic and justified as well as much of today's scientific theory. Normally, such nonsense would be laughable. However, given the status of science today, i.e. god-like reverence, even nonsense is considered good because it calls itself science.
Science is the new religion. Zealots precide.
I was actually trying to start a conversation. I don't care whether you are qualified or not. There are a lot of amateur physicists and mathematicians who work quite hard at picking things up. Do me the courtesy of not assuming my motives. Unless you have clairvoyance? Not much point in being friendly with you is there?
Post by: chiralSPO on 23/01/2015 19:23:14
Youtube is also a friend here:
Video of propeller and rocket operating in evacuated jar:
//www.youtube.com/watch?v=9gFMObYCccU
If you don't trust the vid, maybe go visit the museum?
Some footage from the side of a rocket launching into space:
//www.youtube.com/watch?v=FEom0G30Gic
Also here is footage of our mission to the comet Temple 1.
Deep Impact's view approaching Temple 1
//www.youtube.com/watch?v=XKls-sN56Jk
View of Deep Impact hitting Temple 1
//www.youtube.com/watch?v=dryvDlB1hWA
Please don't waste our time claiming this footage is faked.
Quote from: chiralSPO on 23/01/2015 19:23:14
There is no such thing as a vacuum, you must know that, unless you mean the thing used to clean carpet...So, no "vacuated" jar.
Which museum and what will I be shown there?
The footage is real. However it does not depict what it says it does.
Temple 1 is a model like the rest.
What makes you so sure the film is authentic?
This is my question.
I can make that video in 20 minutes in my basement.
Like YouTube, you say?
//www.youtube.com/watch?v=Jp9Y8I6v_Ds
Skepticism isn't always healthy, and when it is associated with Kruger-Dunning syndrome, it can be very damaging to the patient. Fortunately neither condition is contagious, so the rest of us can walk away unscathed.
However, for those interested in pursuing infamous scientific conspiracies, consider that nobody is sure when Christopher Columbus was born. Now a brilliant navigator would surely be punctilious about such matters, so either (a) he wasn't a brilliant navigator, or (b) he didn't exist. If (a) then we have no reason to believe that he actually went where he said, and if (b) then the entire story is a fabrication. Therefore on all the available evidence, the world is flat. This is entirely consistent with the fact that rockets don't work in space, as all the so-called orbital images are faked to cover up this important fact. It also explains why Americans speak English like Martians: America doesn't exist - they really are Martians, who travel here through wormholes on invisible space buses.
Excuse me, there are two men at the door, wearing white coats. Must go.
You sure have a lot you learn, especially what a vacuum is. The claim in this thread is that thrust can't work in a vacuum because there is no matter to "push" against (or some other nonsense about weight). There is such a thing as a vacuum. See:
http://en.wikipedia.org/wiki/Vacuum
But you need to read that entire page to understand exactly what physicists mean by a vacuum. E.g.
The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%.[3] Much higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10−12) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm3.[4] Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average.[5] According to modern understanding, even if all matter could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, transiting gamma- and cosmic rays, neutrinos, along with other phenomena in quantum physics. In modern particle physics, the vacuum state is considered as the ground state of matter.
All, museums are different so it depends on the particular museum. In the museum of science in Boston they have a tube with a hammer and a feather in it. In one instance they fill the tube with air and drop the items and they fall at very different rates. Then they evacute the tube and then they fall at the same rate. But I don't reacall seeing a demonstration there about a rocket operating in space. It doesn't matter because nobody who knows physics would question it because there's overwhelming evidence of it being the case.
Okay. Let's see you do it. Then again, if you can build things in your basement then build a chamber in which you can create a vacuum and place an estes rocket engine in it with a method to ignite the engine remotely, i.e. outside the chamber and a way to measure the thrust. Have a transparent wall to watch what happens. When there is a vacuum present ignite the engine and you'll see that it will have thrust. Measure it. Do it several times with different pressures in it and you'll find that the amount of thrust does not approach zero as the vacuum approaches zero indicating that pressure is not a factor of the cause of the thrust.
You sure have a lot you learn...
Manifestly.
I am glad to hear you have completed the job [blech]
All, museums are different so it depends on the particular museum.
Ya don't say?
Really, you quote me Wikipedia to prove the existence of the non-existent vacuum?
By my read (you just quoted) it is an APPROXIMATION. You can get close but you can't get it, and the closer you get the better vacuum...
Restore the aether and you solve the problem. Let's say "PURE VACUUM" is mythology, you know, like the Big Bang, and black holes, and antimatter, and...
As for the video, what will you pay me? If it's convincing? Otherwise, you're not very photographically-inclined if you think it CANNOT be made, sorry.
What you consider overwhelming evidence I consider overwhelming parrotry.
The main problem with this thread is that the OP has no idea of how thrust works. His description was nothing but gibberish and shows no understanding of Newton's third law since the OP simply has no grasp of it, i.e.
In space there is no third law and if i believed there was i wouldn't of started this topic.
which is clearly untrue. If a statement is a law of physics then it can't depend on where in space its true. Otherewise it wouldn't be a law.
Take a good long look at just how the OP thinks thrust works, i.e.
Clearly the OP is confusing thrust with the weight of an object. I already explained his mistake but since he doesn't understand physics he was unable to understand the explanation.
His error is this: let us first definne thrust
http://en.wikipedia.org/wiki/Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on that system.[1] The force applied on a surface in a direction perpendicular or normal to the surface is called thrust. Force, and thus thrust, is measured in the International System of Units (SI) as the newton (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 metre per second squared.
In mechanical engineering, force orthogonal to the main load (such as in parallel helical gears) is referred to as thrust.
Essentially Wiki is saying that thrust is a force (described by Newton's 3rd law). The units of thrust is the Newton. Weight essentially has nothing to do with the definition of thrust. The only thing it has in common is that they have the same units. The thrust of a rocket is the force on the rocket which accelerates it through space. The weight of an object is the gravitational force on an object. The OP couldn't understand this so after we explaine his error to him he started insulting us.
I think most of the posts on this thread have become so negative in response to the "style of debate" employed by those arguing that thrust cannot work in space. Science is based in evidence--Since we cannot actually show you a rocket working in space without putting you there yourself (though maybe we can crowd-fund to send one of you into orbit...), and any footage we offer is accused of being faked, and any examples of any space missions lead to talk of vast international conspiracies, what evidence are we left with to discuss? Even basic textbook science is "open to debate" because misunderstanding and/or mistrust of well-established theory.
Perhaps one of you would like to put forth some evidence, beyond thought experiment, that rockets don't work in space?
I would like to mention, however, that skepticism is healthy for scientific maintenance and progress. It is good to have people constantly question even those things that we all take for granted. That said, those who question well-established theory are more often wrong than right, and either way, make few friends. Not everyone who questions dogma is a Galileo. I thank you for performing this necessary and usually thankless part of scientific discourse. But in this instance, you're still wrong.
Thanks for this real post.
which is clearly untrue.
Some people say rules are meant to be broken, exceptions prove them, etc. Newton had no idea of the constituency of space, and nothing says his rules must apply there. Maybe we don't now either. Maybe Newton was wrong, and in fact most of his laws are inaccurate at some scale, or in some (frames). I know I said I agree 100% with Truthseeker, but I meant his overall message, not everything he said, so allow me clarify.
If a statement is a law of physics then it can't depend on where in space its true. Otherewise it wouldn't be a law.
That statement is incorrect on its face. Some alleged laws of physics do not hold up in all circumstances, locations, conditions, etc.
I understand what he means and also why you are frustrated. The problem is your understandings of "weight" vis-a-vis mass, but I think it was discussed already. Actually I think he has a pretty good basic understanding of physics, better than me certainly, it is not my field, but I try :)
Please do better than Wikipedia whenever possible. They are known to be repressive of some information and on the bandwagon on others. But myself I know what thrust is, and how it works, basic physics, not in space, or no vacuum.
A rocket works, for us laymen, by pushing off something. A terrestrial-launched rocket goes nowhere until thrust is given, pushing the rocket off the pad because the expelled air and heat push off the ground. Or the submarine. When launched from a plane, the rocket is dropped from under the wing, and shortly thereafter its thrust begins and the rocket goes forward, this time because it is pushing on air. Were you to take a Saturn-type setup and drop it from, oh, half a mile up, point upwards, somehow, and let it drop, then fire the thrusters, whether or not you make it up, and so escape that gravitational pull, would be a risky proposition. This is just 1/2 a mile, in Earth atmopshere.
No clue there buddy but sounds like more BS retroactive formulae (like diagramming sentences, or speaking in prose).
Essentially Wiki is saying that thrust is a force (described by Newton's 3rd law). The units of thrust is the Newton. Weight essentially has nothing to do with the definition of thrust.
First two yes. The third does not follow, logically.
The only thing it has in common is that they have the same units.
So they do have something to do with each other.
The thrust of a rocket is the force on the rocket which accelerates it through space. The weight of an object is the gravitational force on an object.
The rocket has weight, the thrust also has weight relative its surroundings otherwise how can it be thrust? The force is what is established by the the thrust, read it right.
The OP couldn't understand this so after we explaine his error to him he started insulting us.
Can you direct me to the insult post, I must have missed it. And I don't think he didn't understand it, I think he didn't believe it, or sought to explain it a different way.
I keep needing to leave but I like this post I want to say it is civil and for the most part true. Whether I am wrong or not is the issue, however. I understand and agree it is frustrating in the face of skepticism for something you believe to be true. Hence my questioning.
I make an analogy. There are many photos on the one hand, videos even, of alleged UFOs, and many photos of extraterrestrial objects allegedly taken by NASA from outer space. Seems to me the stack of such evidences would be just as high for both. Is this evidence good enough to conclude the equal validity of both? Jus a question, again, about your authority, how would I decide other than on case by case basis?
False. A rocket pushes off of itself. By forcing propellent in one direction, the rocket goes the opposite direction. If the rocket were pushing off of something, wouldn't it matter what it was pushing off from? Wouldn't it be more effective to push off the hard, stable ground or launch platform than pushing off the air? Well, it doesn't make a difference what is behind the rocket, so I posit that it isn't actually pushing off.
To the OP and Mr. "SteinUntStein"
In an effort to regain some civility in this thread and to likewise offer an explanation for why rockets work in space, please consider the following detailed information.
Place your attention to the inside of the rocket. A tube, if you will, with one end open to space and the other end sealed off. An explosion takes place located in the center of the tube. From this location at the center, there will be force directed in two basic directions, out the back at the open end and likewise, toward the front end which is sealed off. The force directed out the back end is not what propels the craft, it is the force applied toward the front of the rocket. Because the explosion is initiated in the confines of the rocket, the sealed end of the craft feels the push from the pressure wave and experiences movement away from the initial explosion. Thus the rocket moves thru the vacuum. The expanding gases out the back of the rocket have little to do with the motion of the craft.
Even on Earth, if you plug up the exhaust of a rocket it will go nowhere.
Your analogy is explaining things in a half-empty/half-full glass sort of way. Yes what you say is half true. The rocket does go up (or straight out from under the wing...well kind of straight up, I mean those manned trajectories themselves could use examination...) because of pushing against the rocket. BUT if there was no thrust there, outside against the resistance of air, there would be no movement.
Blow up a balloon. Keep the end closed. No forward movement. Let the hole open, you get forward motion. You get it because the air inside is being expelled outside. Use the air inside as analogy for the spend fuel. Without exhaust it goes nowhere. Seems to me in an alleged vacuum that air would be expelled, but just kind of dribble out the end.
Yes a rocket pushes off itself, but it needs a catalyst, as you say very next sentence "by forcing propellant in one direction."
No propellant force, no motion, necessary vs. sufficient conditions.
Blow up a balloon. Keep the end closed. No forward movement. Let the hole open, you get forward motion. You get it because the air inside is being expelled outside. Use the air inside as analogy for the spend fuel. Without exhaust it goes nowhere.
*That ↑* is a perfect explanation! [;D]
Seems to me in an alleged vacuum that air would be expelled, but just kind of dribble out the end.
But this ↑ is mistaken. If anything, the air would be expelled faster into a lower pressure environment or vacuum, not slower.
Quote from: chiralSPO
That's precisely the case. The rate of flow is a function of the difference in pressure.
The exhaust would just kind of be absorbed by the vacuum (alleged) of space. Low pressure is also not the same as no pressure (vacuum).
Absolute vacuum is unachievable. But we can call very low pressures "partial vacuum," or even just shorthand it as "vacuum" because no one would be expected to confuse the "vacuum" being discussed with absolute vacuum.
The vacuum of space is also actually just extremely low pressure (down to about one particle per cubic meter!)
I'm not exactly sure what you mean by "absorbed by the vacuum."
Time try a molecular picture of pressure and thrust!
Pressure (P) is proportional to the number of gas molecules (n) per unit volume (V), as well as proportional to temperature (T, on the Kelvin scale). Hence the handy equation P = nRT/V, where R is a constant.
If we have a box of some gas at room temperature (273 K) then the gas molecules will be zipping around inside the box, bumping into the walls with a rate determined by n/V, and kinetic energy determined by T. The pressure is a result of this: a greater number of molecules in the box will hit the walls more often, and at higher T, they will hit the walls harder.
If we now imagine an immobile wall dividing the box into two compartments, we can calculate the pressure on either side of the wall, given the number of gas molecules and volume of each side (let's assume T is the same on both ends of the box, so the molecules are all moving with the same average kinetic energy). If the left side has twice the number of molecules per liter as the right side, there will be twice as many molecular impacts per second against the left side of that wall as on the right side. As defined, the wall can't move, but if we allowed it to move, it will go to the right, being pushed by all of the molecules on the left. As it moves, the density of gas on the left decreases (because the available volume increases and number of molecules remains the same), and the density of gas increases on the right (because the volume is decreasing). Eventually the densities (pressures) equalize, and the wall stops moving because the molecules pushing it from the right perfectly balance the molecules pushing on the left.
Let's try this thought experiment again, but with an immobile wall that has a hole in it that we can open by pressing a button. Initially there are twice as many molecules on the left side of the box as on the right side, and both sides have the same volume (and temperature). Let's say the hole is circular, with an area of 1 mm2. While the hole is closed, molecules from each side of the box are bumping into the cover and bouncing back the other way (just as above). In any given second, there are twice as many molecules hitting the left side of the hole-cover as are hitting the right side. Now, we push the button, and the cover slides over, opening the hole. Now, instead of bouncing back, the molecules pass right through the hole, with twice as many molecules per second passing from the left side to the right side as there are from the right side to the left side. There are molecules going both ways through the hole, each with the same average speed, but the overall rate of flow is from the left to the right. If the density on the left side of the box were 10 times that of the right side, then there would initially be ten times as many molecules going from left to right through the hole. As the number of molecules on the left fall, and the number of molecules on the right increase, the rate at which molecules cross from right to left approaches the rate they cross from left to right, eventually becoming equal. There are still molecules crossing the hole, but when there are the same number going each direction, the overall flow of gas has stopped.
Now lets imagine that there are two boxes, one inside the other, and the smaller (inner) box has a hole that can be opened with a button. The inner box has 1000 times as many gas molecules in it, and is 1000 times smaller than the outer box (so the ratio of molecular densities is 1000000:1). This means that there are 1000000 times as many molecules bumping into the inside of the box as there are hitting the outside of the box (it will explode if the box isn't strong enough, but let's say it doesn't). When the hole is opened, 1000000 times as many molecules per second will move through the hole from the smaller box into the larger box, as will move from the larger box to the smaller box (note: if the larger box had an extremely low density of gas molecules, there might not be any that pass into the smaller box through the hole). So overall, molecules are leaving the inner box though a hole that's on one side.
The force exerted on the inner walls of the inner box is unbalanced now, as there are fewer molecules hitting the wall with the hole as there are hitting the wall without the hole. So if the inner box is free to move, it will naturally move away from the side that has the hole (being pushed by the gas inside it). As long as the pressure inside the inner box is greater than the pressure of the outer box, there will be a flow imbalance and the inner box will move accordingly. That is thrust.
No I'm afraid you are wrong again. The exhaust would just kind of be absorbed by the vacuum (alleged) of space. Low pressure is also not the same as no pressure (vacuum).
Presumably you are happy to admit that rockets work OK at low altitude. You might also admit that atmospheric pressure decreases with altitude - or is my altimeter operated by fairies? So at what altitude do they stop working?
Nowhere in the cosmos does a perfect vacuum exist. So, I'm afraid you are misinformed.
The exhaust would just kind of be absorbed by the vacuum (alleged) of space.
As I said above, the thrust on, say, a high pressure gas container, is a function of the pressure outside the container and the pressure inside the container. If the pressures are equal ten the container doesn't accelerate. If the outside pressure is near zero then the thrust is at a near maximum. In between those extremes the thrust is also in between and is an increasing function of the difference.
ChiralSPO: I appreciate the explanation attempt however there is one problem, it's that the box would be need to constructed of such material that nothing could go through it. Many perceived impermeable materials can be penetrated by the likes of subatomic particles, light, etc. Also, if that box is truly sealed, in the absence of any compelling factor, there should be no movement because any alleged vacuum would make that an impossibility. Maybe I'm missing how this applies to either thrust in space or the existence of any vacuum.
AlanCalverd: They stop working when there is no atmosphere at all. No atmosphere = no means of propulsion. Pretty basic actually. Maybe your altimeter is off, possible you know ;)
Ethos: I in fact was the first person on this board to assert the non-existence of the vaccum in relation to the thrust question.
PmbPhy: The converse (vacuum exists) is taken as a fundamental truth, without the qualification, about the constituency of space.
There is no vacuum, as Ethos has confirmed. If indeed thrusters work in space IT MUST BE BECAUSE the space you are in IS NOT a vacuum.
The box doesn't have to be impervious to everything, just the gas that it contains.
The box won't move when it is perfectly sealed, but will begin to move if a hole is opened on one side, allowing the gas to escape (assuming the environment has a lower pressure of gas).
I know it was a really long post, but I suggest giving it another read to see how it applies to thrust and pressure differences.
We understand that space is not a true vacuum, but that is not why thrusters work in space. If you know there is no vacuum in space, why claim that thrusters can't work in space, and be so hostile to the notion of spacetravel?
By the way, let's try to keep this civil, please... everyone...
Nowhere in the cosmos does a perfect vacuum exist. So, I'm afraid you are misinformed, or more likely, you are just being contrary and or contentious.
So the moment you introduce a rocket, it's no longer "space" (particularly if it is belching out exhaust gases), ergo the question is meaningless.
They stop working when there is no atmosphere at all. No atmosphere = no means of propulsion. Pretty basic actually.
Wrong.........................A rocket needs no air behind the exhaust to move. The motion of the rocket occurs because; While the force is applied in both directions, front and aft, the only end that feels the force is the sealed end.
So in your experience (not opinion - this is a science forum), rockets become less efficient as the atmospheric pressure decreases. Have you told NASA and RFSA? Or the Chinese satellite companies, and everyone else who regularly flies rockets? Their experience seems quite different from yours.
It's a very well established fact which can be derived as a theorem based on Newton's Third Law, and verified countless experimentally and in practice countless times, that what you keep claiming is 100% wrong? It's been demonstrated time and time again with every launch by NASA and other agencies of rockets into space that your claims are 100% BS. They simply do not stop working or even become less efficient when there is less atmosphere.
It's quite an amusing and interesting exercise, to claim some fundamental law of physics doesn't apply in some fairly common situation (rockets in space are fairly common these days - probably about 10,000 launches since sputnik). It allows one to refresh one's understanding of how these laws apply. But to persist as if serious smells of trolling. Many people are unable to grasp the principles of aerodynamics, yet they don't deny that planes fly.
The idea that if you don't understand it, it can't happen, or that the world necessarily conforms to one's naive understanding of it, is understandable, but to deny such a vast amount of evidence is perverse or delusional.
I've had a couple of complaints about this topic.
Please strive to keep the comments civil, and on topic.
I have been going through and removing some of the personal attacks, but I would expect board users to refrain from petty name calling and belittling others.
- Moderator -
Well this should be my last post since I have been censored and singled out as an insulter when all I am doing is counter-punching.
For everyone who "complained", and you know who you are: Thanks for proving my point. ALL my posts have been on topic and ALL were civil unless I was insulted first.
Your science is a fairy tale, a modern myth believed rabidly, tooth and nail, with all the blind acceptance of religious zealotry.
None of you here have been in space. None of you have seen thrusters work in space. None of you, I presume, has made any contribution to real science.
You are just parrots, rehashing the "science" I first knew as bad a decade ago.
So, in humble gratitude for your lack of any help, for your backstabbing and clandestine complaints to moderators because you got your little feelings hurt, because you cannot fight your own battles and prefer to ban the problem rather than correct it, for being hypocritical (YOU HERO FAGS can insult, but noone else can...), I want to say, go **** yourselves, and thanks for the new mission ;)
The understanding concerning propulsion has been misunderstood by the layman ever since rocketry first came on the scene. I remember my physics teacher asking our class in high school how we would explain the motion of a rocket. 100% of the class got it wrong! The common interpretation was that the exhaust coming out of the aft side of the rocket was pushing against the air behind it. Even after our physics teacher attempted to explain that the reason for the rockets acceleration was caused by the force applied to the forward end of the rocket, many of us were still questioning how that could be.
Not until I was much older and attending college did I finally understand the laws of motion. So when people don't understand how these phenomenon work, I can appreciate why they have their doubts. Nevertheless, when individuals resist the facts and refuse to be taught why things react the way they do according to the laws of physics, it becomes quite frustrating.
Given some time and proper examination of all the facts, those who misunderstand why a rocket works will eventually have that light bulb go off in their minds. These moments of growth in our understanding are the WOW moments in our lives and this is why I love science!
Who're you kidding?? We all know that you were the one to respond with insults when we explained to you that you were wrong and ignorant of the correct physics. Like too many people you mistook the term "ignorant" to be an insult when in fact all it means is you lack knowledge in a particular area. We're all ignorant in some field but you used that and other things to launch ad hominem responses. Cliff is far to smart to be fooled by your claims. He's read your responses and knows what you did all along.
The easiest way to understanding this is to look at the simplest situation. In a vacuum, think of a coin with a firecracker next to it right above its flat side. When the firecracker detonates the fragments smash against the coin and bounce off of it. Newton's third law tells us that the coin will rebound. You can look at a rocket engine as a controlled continuous explosion. This has nothing to do with the presence of an atmosphere. In fact it doesn't work as well with an atmosphere present.
There seems little point in discussing this further with SuS until he has answered my question: at what point, during its ascent through the atmopsphere, has he observed the efficiency of a rocket to decrease?
Science is begins with data, not conjecture or analogy, and this is a science forum.
I agree Alan, but some members come to our forum expecting us to answer their questions in the affirmative while feeling no responsibility to answer ours. Such displays only prove their goals have nothing to do with sharing information but everything to do with exaggerating their egos.
He seems to refuse to answer any question which so obviously proves him wrong. For example: how did all the communications satellites get into orbit.
Lately he's been trying to confuse the issue by using the fact that a perfect vacuum doesn't exist. He doesn't really grasp how small the pressure is even 200 miles above the surface of the Earth. For all practical purposes, especially this one, it can be assumed that the pressure is exactly zero.
SteinUntStein seems to be one of a growing number of 'skeptics' who don't understand the application of Newton's Laws in certain situations. For example, this painful thread on CluesForum (http://cluesforum.info/viewtopic.php?f=23&t=1632). There seems to be an associated conspiracy theory about NASA...
That thread is absolutely horrible. Sometimes I think that talking about physics should be banned by those who don't know what they're talking about. Lol!
It's as if none of these crackpots have ever follow the derivation of the rocket equation or when they try they say incredible stupid things. Like in that thread they say
This crackpot doesn't understand anything and its evident in his statement The problem with applying Newton's 3rd is that the rocket's propellant does not generate force in a vacuum according to the laws of physics and chemistry. which is total rubbish. He's making a ridiculous claim with no attempt at backing it up. The chemicals detonate, some go out the back and some hit the nose end of the combustion chamber. The waste products of the explosion bounce off the chamber wall and by Newton's third law the chamber wall recoils taking the rocket with it. It's as simple as that and they simply can't grasp it. Yet they can't even get to the first point where the propellant generates a force on the chamber wall. Oh puleeeeseee!!!
Here's another nut in that thread
Short answer: Yes a gun recoils in space. No, the analogy does not apply to rockets.
Longer version: Shooting a gun in space would happen theoretically as follows: pressurized gas accelerates the bullet through the barrel until the bullet leaves the muzzle. At that point the gas that was pushing the bullet escapes without doing any more work i.e. via free expansion. The energy of the bullet (its momentum) travels with the bullet and the gun recoils by principle of conservation of momentum.
The gun analogy does not apply to a NASA-type space rocket as their pressurized gas escapes without doing any work at all. A NASA rocket is a gun without a bullet.
This nut can't figure out his mistake. What he did wrong was to ignore that its the recoil itself that makes the rocket accelerate and its the gas that is the bullet. Sort of like shotgun shot. Reading this nonsense makes me real angry because it leads people to make mistakes and never recover from them so the live in ignorance and it hurts them somehow or another.
Either these crackpots never ask themselves why all the physicists that have existed on the planet since the rockets was invented know this and they don't or they think they're smarter than the rest of the planet. That's arrogance in the extreme.
The derivation under MITs website is at
http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node103.html
Want to know what really pisses me off about all of this? It's the fact that experimentation and observation dictate that rockets work exactly like we're (e.g. NASA, MIT etc) state that it does.
Too much (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.bikeforums.net%2Fimages%2Fsmilies%2FDeadHorse.gif&hash=bdd9764afb3cfe9ced1d01976c898a79)
I'm closing this thread.

redpajama_set_name: RedPajamaCommonCrawl