A car's bumper is designed to withstand a 7.20 km/h (2.0 m/s) collision with an immovable object without damage to the body of the car. The bumper cushions the shock by absorbing the force over a distance. Calculate the magnitude of the average force (in N) on a bumper that collapses 0.210 m while bringing a 860 kg car to rest from an initia speed of 2.0 m/s. (Enter a number.) N +