500
Using the words inertia and unbalanced force. Explain why when you slam on the breaks in car your body lurches forward.
When you slam on the brakes in a car you are applying an unbalanced force to the car, which results in the car accelerating (slowing down). Because of inertia, the resistance to an object to a change in its motion, your body wants to keep moving at the same speed it was before the car braked.