A vehicle is travelling at 72 km/h (20 m/s) when the driver sees a couple walk out on to the road 20m ahead (d=20m). The driver brakes immediately and stops just in time to avoid impact (i.e braking distance is 20m). The vehicle decelerates at a constant, gradual rate without skidding.

If the mass of the car is 1000kg, what was the work and power required to decelerate the vehicle?