Newton’s Third Law

For every action there is a reaction equal in magnitude and opposite in direction .
F1 = – F2

Applications:

1- When the gun is fired from a gun forward , the gun is rebounded backward

also..

2- When a hammer hits a nail by a force the nail reacts by equal opposite force

But why is the nail driven in the wood then ??!!
there are Two forces are acting on the nail :
The first one is the hammer hitting the nail the nail answers by an equal force
The wall is affected by hitting the hammer so the wall has a reaction on the nail which is smaller than the original force acting on the nail (hammer hitting) so the nail can be driven in the wood and the net force becomes in the direction of the greater force which is the action of the hammer

3-A Bed of nails

Magicians use a bed of nails with a heavy block on their chests but the nails don’t penetrate their bodies and they are not harmed why??
Because the force is distributed over a large area of nail tips , so the force of each nail is so small and the body’s reaction can resist it (body’s reaction is equilibrium with the pressing force of each nail )

4- The Ballon

5- The rocket

thrust exerts a force upon the rocket , the rocket answers by a force equal in magnitude and opposite in direction