Please help I am lost

Question

A 1,800 kg car moving at 6.0 m/s is stopped by the action of its brakes. The work done by the car's brakes is ____ Joules.

Answer 1

The work done by the brakes is the change in the kinetic and potential energy! Assuming the car is on level ground, there is no change in potential energy.

The change in kinetic energy is (1/2)mv² - o which is the kinetic energy at the breaking velocity and then

zero as the vehicle stops.

KE₂ - KE₁ = .5*(1,800 kg)*(6 m/s)² - 0 = 32,400 kg-m²/s² = 32,400 joules