An automobile of mass 1000 kg is travelling at 72 km h on a straight
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
An automobile of mass 1000 kg is travelling at 72 km h−1 on a straight, level road when the driver applies the brakes and the car comes to rest after deforming its front crumple zone.
(i) Calculate the kinetic energy possessed by the car just before braking begins.
(ii) If the front of the car compresses by 0.50 m while coming to rest, determine the average retarding force exerted on the car during the collision.
(iii) Modern designs increase the compression distance to 1.5 m. For the same initial speed, calculate the new average retarding force and find the percentage reduction compared to part (ii).