Question

newtons third law states that every action has a equal and opposite reaction but when we hit someone,he may fall down but our hand does not come back. y?

Answer 1

When you hit him in the face with your hand, you can, according to Newton, say that his face hit your hand. In fact, if you transfer 10 newtons into his face, 10 newtons is transferred back into your hand. This is why they teach you not to clench your fist before a strike in most punching martial arts; instead you have you fist slightly open and let the compression absorb the counter-force mechanically on your end.

Answer 2

\[F=ma \]
force of hand on body may have more acceleration but less mass
but the body has less acceleration and more mass
so the hand does not come back