Forces 2

Forces 2

1. acceleration= velocity change/time

2. work done- the energy transferred when a force causes movement= force x distance (joules, J)

3. air resistance- the force acting against motion, caused by collision with air molecules

4. power- the rate at which energy is transferred. measured in watts (W)

   • energy (work done) / time= power

5. friction- any force which acts against motion (eg. air resistance)

6. GPE- energy gained when something is lifted up, against gravity (J)

7. force- something which tires to change the velocity, shape or direction of an object (newtons, N)

8. resistive forces- the sum of all frictional forces acting on an object

9. safety includes trying to reduce the maximum force that a person experiences in an accident, usually by increasing the time of collision

   • force= change in momentum/time

10. kinetic energy- energy due to movement

    • 1/2 MV squared

11. resultant forces- the sum of all forces, if this is zero= no change in speed

    • if not zero, the acceleration depends on mass and force, as F= MxA

12. conservation- some physical quantities are always the same in total (eg energy, momentum)

13. momentum- a measure of the difficulty in stopping a moving object, a conserved quantity (mass x velocity)