-To measure resistance an ohmmeter is used.
The resistance of a given resistor or conductor grows with the length of conductor and specific resistivity of the material, and decreases for larger cross-sectional area.
A wire carrying alternating current has a reduced effective cross sectional area because of the skin effect.
Thermal Resistance is a heat property - and a measure of a temperature difference, by which an object - or material resist a heat flow (heat per time unit or thermal resistance).
-Work Done (j) = Force (n) x Distance (m)
-Work Done (j) = Power (w) x Time Taken (s)
- 4 (n) x 5 (m) = 20 (j)
- 6 (w) x 120 (s) = 720 (j)
Work done is movement against the force of friction.
Gravitational Potential Energy
Gravitational Potential Energy (j) = Mass (kg) x Gravitational Field Strength (n/kg) x Height (m)
-30 (j) = 0.5 (kg) x 10 (n/kg) x 6 (m)
-20 (j) =1 (kg) x 10 (n/kg) x 2 (m)
-Speed (metres per second) = Distance (m) /Time (s)
-450 (m) /15 (s) = 30 (meters per second)
-600 (metres per second) = 6000 (m) /10 (s)
-Distance (m) = Speed (meters per second) x Time (s)
-100= 25 x 4
Distance - Time Graph
When an object is stationary the line is horizontal the distance doesn't change (the object doesn't move).
When a line is diagonal going upwards then the object is going at a steady speed, the steeper the line the faster the object is moving.
If the line is going diagonally downwards the object is slowing down going back to its starting speed.
-Acceleration = Final Velocity - Initial Velocity/Time
-20-0/6 = 20/6 = 3.3 (metres per second)
-50-8/3 = 42/3 = 14 (metres per second)
When two forces are balanced the object is stationary.
Ticker Tape Timer
Resultant force- on an object is the single force that would have the same effect as all the forces acting on the object.
-Air resistance + Friction = 400n+400n = 800n
-Forward Force - Backward Force = 1000n - 800n = 200n
Air resistance is a frictional force that opposes the motion of a solid object moving through the air.
Factors effecting air resistance:
-Size and shape.
Laws of Motion
- stationary objects stay stationary.
- moving objects stay moving at the same speed in the same motion.
- If the forces on an object aren't balanced the object will accelerate in the direction of the force.
-The weight of an object is the force on the object due to gravity.
-Weight (n) = Mass (kg) x Gravitational Field Strength (10n).
Weight is measured in Newtons.
Mass is measured in Kilograms.
Gravity is equivalent to 10 Newtons.