Question

According to Newton's third law,for every action there is an equal and opposite reaction.

If I apply a force to door, according to the law ,it should also exert same force .So the two force are equal and opposite, they may cancel out and there is no movement.But the door moves ? How is it possible?

Also according to the law,it states that unbalanced forces are not real since every force has equal and opposite pair,they cancel out to form balanced force .But how?

Answer 1

Action reaction force pairs act on different bodies. So when you apply force on the door it moves. The door also applies the same force on you but since your mass is more than the door, you do not experience any observable acceleration that is any motion. You also have to consider friction in this case between you and the floor and between the door and it's hinges. The essence here is that third law pair forces act on different bodies and hence do not cancel each other.