a car of mass 12,000 kjg is moving at 40m/s along a strong road. The driver brakes and the car goes 800 meters before stopping. What was the magnitude of the average force of friction (inN) between tires and road?
Is the mass a typo?
12,000 kg is too big for a car
force * distance = change in kinetic energy
800 F = (1/2)(12,000 ?)(1600)