6) What equation links change in momentum, time and force? … force = change in momentum / time (1 mark)

7) A bullet of mass 0.004kg moving at a speed of 90m/s is stopped by a little bullet-proof vest in 0.0003s. Calculate the impact force.

0.004 x 90 = 0.36 0.36/0.0003 1200N (2 marks)

8) At turn 8 of the Spanish grand prix Heikki Kovalainen went off the track at 100miles per hour (45m/s). The car hit the tyre wall and came to a stop in 0.08s. A F1 car has a mass of 604kg. Calculate the force on the car.

45 x 604 = 27180 27180/0.08 339750 (2 marks)

9) A car of mass 900kg is travelling at 13m/s when it hits another, stationary, car of mass 750kg. Both cars then collide into a wall and come to a stop with an acceleration of -0.5m/s2. How long did it take the cars to com to a complete stop and what was the force on the cars during this time?

A – 900 x 13 = 11700 kg m/s

f = ma = 1650 x 0.5 = 825N

AB - time = change in momentum/force = 11700/825 = 14.2s

(4 marks)