Newton’s Third Law of Motion: To every action, there is always an equal and opposite reaction.

Important points about the Third Law

(a) Forces always occur in pairs. Force on a body A by B is equal and opposite to the force on the body B by A.

(b) There is no such cause-effect relation implied in the Third Law. The force on A by B and the force on B by A act at the same instant. Any one of them may be called action and the other reaction.

(c) Action and reaction forces act on different bodies, not on the same body.