Every+action+has+an+equal+and+Opposite+Reaction

=Equal and Opposite Reaction - For every action there is an equal and opposite re-action. Which means when you sit down a chair the chair pushes back so that you will not fall through it. You could not really do much without it because you would be falling through everything. Same as a chair a trampoline pushes back so you can jump on it instead fall through it.=