Question

When a boy jumps out of a boat , the boat moves backwards why?

Answer 1

Answer:

because of the frictional force the boat moves backward

Answer 2

The answer to this is given by Newton's Third Law of Motion.

According to the Law, it states that :

Every action in the world has equal and opposite reaction

Mathematically :-

$\boxed{F_{AB} =(-F_{BA})}$

Now coming back to question :-

As we jump from the boat we gain a forward motion while due to the forward motion the boat acquires a backward motion.

We jump in forward direction but due to our applied force the boat moves in opposite that is backward direction.

This satisfies the Third Law of Newton's Motion.

Our Action in front gives a reaction in backward direction and boat moves backward with the same applied force and velocity we gained.