Question

many automobile passengers suffer neck injuries when struck by cars from behind. how does newtons law of inertia apply here?why would a headrest help guard against whip-lash

Answer 1

Think of Newtons first law: Heads at rest tend to remain at rest, even if the car they are in is struck from behind and then lurch forward.

The headrest moves the head with the car. Without it, the head wants to remain stationary.