Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. When a force acts on an object, the object exerts a force of equal magnitude but opposite direction on the object applying the force. Examples given include a swimmer pushing off a wall, where the wall pushes back on the swimmer with an equal force, and a rocket, where the exhaust gases push backward on the rocket with an equal force, propelling it forward.

1. Newton’s Third Law of Motion