A truck with a mass of 2,000 kg is traveling at a

constant velocity of 40 m/s. What is the net

force acting upon the truck?

a truck mass 2000. kg is travelling at 45 m/s when the driver spots a policeman ahead. The driver applies the brakes lightly for 3.0 s until he slows down below the speed limit. If the average force applied to the brakes was 1.4 x 10^4 N, by how much did the kinetic energy of the car change?