a) According to Newton’s third law of motion, whenever a body exerts a force on another body, there is an equal and opposite force experienced by the first body.
Following are the two examples:
i) When a man is coming out of a boat an equal and opposite force is experienced by the man as he applies a force in the backward direction which pushes him forward.
ii) When a gunman fires a bullet, he experiences a jerk. This is because for a bullet to move forward, a backward force is applied by the bullet making a jerk.
b) When a fireman directs a powerful stream of water on a fire from a hose pipe, the hose pipe tends to go backwards because of the reaction force of water that is rushing from the hose pipe in the forward direction.