# Newton's 3rd law [closed]

So i read this in some article on the net

Consider a boy is standing at distance of 10 metres from the wall. Boy holds a rubber ball and cloth ball in his hands. Firstly, the boy throws rubber ball with force 2N (Newton) on the wall. The rubber ball after striking the wall rebounds to 10 metres. Thus, action and reaction are equal in this case. Secondly, the boy throws cloth ball with an equal 2N force on the wall. The cloth ball rebounds to five metres. Thus action and reaction are not equal.

Is this really right? o.O

P.S: i dont have any background in physics and hence this question

The "actions" of Newton's Third Law are Forces, not distances, velocities or even momenta. Your distance from the wall and the distance that the ball rebounds have nothing to do with each other under the 3rd law. The "Opposing Force" when you throw the ball is the force that is pushing you back against the ground that you are standing on. The Opposing Force when the ball bounces off the wall is the force that is pushing the wall against its foundations.

If you stand on Teflon ground wearing Teflon shoes, you will not be able to throw the ball as far, because you cannot get the usual opposing force from the ground and you will be pushed back a little.

If the wall has no foundations (and is thin and also not very heavy) then the ball will not bounce as far and the wall may fall over, again because you lack the usual opposing force that was being supplied by the foundations.

All the Third Law really says about your ball bouncing off the wall is that the implicit forces applied to your ball and the those applied to the wall are the same, but opposing.

What the difference in their bounce is really about is a difference in how much energy is lost (dissipated) by one ball versus the other. The cloth ball dissipates more energy than the rubber ball, probably by redirecting it into changing the shape of the cloth ball.

• You don't throw something with a force, but with a force over some finite time (called an impulse)
• The same for the bounce, which is also and impulse.
• The bounce speed is different, but that is not an indication that the bounce force is different necessarily.
• The 3rd law talks about the interaction in a contact pair (the ball and the wall) at any instant, and not between the throwing and bounce which happens at different times.

You might want to find a page from a university course in Physics 101 to get credible information because the statement in your post is misleading and incorrect.

Energy can neither be created or destroyed but only changed in form. This is an area known as entropy. The energy given to the rubber ball E=ma accelerated it tward the wall it compressed stored the energy and released it again for the bounce and it went 10m.When the cloth ball was thrown most of its ma was absorbed by the wall,and he must have thrown it pretty hard to get it to bounce 5m. If they had been steel balls bouncing on a steel surface energy absorbtion would not have been noticable. I'm not sure if this answer is good enough.