Question

Why does a gunman get a jerk on firing a bullet?

Answer 1

Hint: We know about the third law proposed by the great scientist Sir Isaac Newton. When two bodies are in contact, Newton's third law states that they apply forces to each other that are equal in magnitude and opposite in direction. The law of action and reaction is another name for Newton's third law of motion.

Complete answer:
When a gunman fires a bullet, the gun exerts a force on the bullet to throw the bullet out through its barrel. The force exerted by the gun on the bullet in turn exerts a force on the hands of the gunman. This is due to the reaction force by Newton’s third law of motion. The jerk experienced by the gunman is a perfect example of the action-reaction motion of the third law.

Examples like normal reaction forces, tension forces, gravitational forces, etc… are all of the action-reaction examples. Here, we can assume by this example that there is not a single force action i.e. only on the bullet, but there is another force too which is equal in magnitude but opposite in direction acting on the gun which in turn applies jerk on the hands of the gunman.

Note: We need to keep in mind that no force acts in a single manner, rather every force acts in pairs. This is why everywhere Newton’s third law is valid for each kind of force.The other two laws of Newton's are also valid everywhere but it is not our concern. Here, we just need to keep in mind that whenever we apply a force we have to face the force in turn applied to us.