Hello Everyone. This is my fourth posting. I am basically a non-science person learning some basics physics with a on-line program. Please review my homework questions and my answers. I know that I am confused on some concepts. Any help will be appreciated greatly. Physics Questions – Round 4 1. A sports car with a mass of 1000 kg travels down the road with a speed of 2 m/s. Which is larger, its momentum or its kinetic energy? a. momentum b. kinetic energy* c. they are equal d. the two cannot be compared 2. Which of the following objects has the largest kinetic energy? A mass of _____with a speed of _________. a. 6 kg .....2 m/s b. 4 kg .....3 m/s c. 2 kg .....5 m/s d. 6 kg .....3 m/s* 3. Under what conditions is the kinetic energy conserved in a collision? a. It is always conserved* b. When the collision is totally elastic c. When there is no outside force d. When there is no friction 4. A 3-kg toy car with a speed of 6 m/s collides head-on with a 2 -kg car traveling in the opposite direction with a speed of 4 m/s. If the cars are locked together after the collision with a speed of 2 m/s, how much kinetic energy is lost? a. 10 J b. 28 J* c. 60 J d. 70 J 5. A tennis ball on the end of a string travels in a horizontal circle at a constant speed. The circle has a radius of 2 m, the ball has speed of 3 m/s, and the centripetal force in 1.5 N. How much work is done on the ball each time it goes around? a. zero b. 6 J c. 10 J* d. 12 J 6. Which of the following properties of a ball is conserved as it falls freely in a vacuum? a. kinetic energy* b. gravitational potential energy c. momentum d. mechanical energy 7. If a 0.5-kg ball is dropped from a height of 6 m, what is its kinetic energy when it hits the ground? a. 3 J* b. 9 J c. 30 J d. There is not enough information to say 8. An elephant, an ant, and a professor jump from a lecture table. Assuming no frictional losses, which of the following could be said just before they hit the floor? a. They all have the same kinetic energy b. They all started with the same potential energy c. They will all experience the same force on stopping d. They all have the same speed* 9. A 1-kg ball falling freely through a distance of one meter loses 10 J of gravitational energy. How much does the kinetic energy of the ball change if this occurs in vacuum? a. gain of 1 J b. gain of 10 J* c. loss of 1 J d. loss of 10 J 10. A block of wood loses 160 J of gravitational potential energy as it slides down a ramp. If it has 90 J of kinetic energy at the bottom of the ramp, we can conclude that: a. mechanical energy is conserved b. momentum is conserved c. 250 J of energy was lost d. 70 J of energy was lost* Thanks for taking the time to help a true novice.