a car's bumper is designed to withstand a 3.60 km/h (1.0 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 0.270 m while bringing a 840 kg car to rest from an initial speed of 1.0 m/s. (enter a number.)