Question

A car of mass 650 kg is moving at a speed of 0.7 m/s. A man pushes the car, increasing the speed to 2.2 m/s. How much work did the man do?

Answer 1

By the work energy theorem the work he did is equal to the change in energy of the car.
E=(1/2)m[(v2)^2-(v1)^2]
E=325(2.2^2-0.7^2)
E=325(4.35)
E=1413.75J
This is the car's increase in energy and is thus how much work the man did.