A car (1000 kg) is going 20 m/s on a level road and slams on the brakes. The skid marks are 25m long.
a) What is the change in kinetic energy during the skid?
b) What is the work done on the car by the road?
c) What is the work done on the car by gravity?
d) If the force of friction is constant over the 25m skid, what is magnitude of the force?