Question

If a man jumps out from a boat, the boat moves backwards. Why?

Answer 1

When a man jumps out of a boat to the bank of the river, the boat moves backwards, away from him. This is due to the fact that to step out of the boat, the man pushes the boat with his foot in backward direction. The push of the man on the boat is the action. The boat exerts an equal force on the man in forward direction which enables him to move forward. This force exerted by the boat on the man is reaction. Since the boat is floating on water and not fixed, it moves backward due to the force exerted by the man.