Newton’s III Law of Motion

Newton’s third law of motion states that to every action, there is an equal and opposite reaction. That is, in any pair of bodies acting forces on each other, force exerted by one on the other is equal in magnitude and opposite in direction to the force exerted by the second body on the first body. That is
If you give a slap to a child, the child cries due to pain. The pain is caused due to the force exerted on him. At the time the child feels pain; you also feel pain on your hand. The pain on your hand must be due to some force acting on your hand. What is that force? In fact, when you give a slap to the child, you apply force on the child’s face. At the same time, the child’s face also exerts force on your hand. The pain on your hand is due to the force exerted by the child’s face on your hand. The force exerted by your hand on the child’s face is called action. The force exerted by child’s face on your hand is called reaction. Hence, the action and reaction are forces which act on different bodies. The action is the causes and the reaction is the effect.