Newton's Laws Of Motion - Engineering Science

Newton’s 3rd law of motion:
For every action there is an equal and opposite re-action.

The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs - equal and opposite action-reaction force pairs.

Consider a sprinter on the starting blocks, when the starting pistol is fired the sprinter will exert a force between their feet and the starting blocks to push off quickly into motion. Whatever force the sprinter exerts on the starting blocks the same value of force will be pushing back but in the opposite direction, this is what helps launch the sprinter into motion.