Answer to Question #251 in Mechanics | Relativity for sadaf

Question

According to third law of motion we say that "action and reaction are equal in magnitude but opposite in direction" but if we throw a ball from a building to earth it will touch the earth and go back but it will not reach to the floor of building from which we had throw the ball. Can you explain this?

Answer 1

The thing is that a ball loses some energy because of the friction with the air while it falls. Also the touching itself is not ideal - there are deformations during it and due to this ball loses some energy in this way too.