Question

When a boy jump out a boat , the boat move backward. Why?

Answer 1

because newton third law say

to ever action there is an equal and opposite reaction

ex if you push a wall. wall is also push you with an equal fore

in case of this

if we jump from boat we push boat and boat move backward and we know that to every action there is an equal and opposite reaction so boat also push us forward

and if boat doesn't move backward then we doesnt move forward

Answer 2

because when the person is jumping from a boat he aplies force on the boat which is called action and the boat acts the equal force on the person which is equal and opposite in the direction to the action force which is called as reaction.