A car of mass 1400 kg travels along a level road. The driver applies the brakes and a constant braking force of 7000 N brings the car to rest.
Explain why the work done by the braking force is equal to the kinetic energy of the car before braking.
Show that the braking distance of the car from a speed of 20 m/s is 40 m.
The speed of the car is increased by 50%. The braking force is the same.
Calculate the new braking distance.
A council reduces the speed limit on a road from 30 mph30\ \text{mph}30 mph to 20 mph20\ \text{mph}20 mph.
Explain how this changes the braking distance of a car on the road.