Newton's third law states that for every action, there is an equal and opposite reaction. This doesn't make sense to me, because it seems as though everything would cancel out and so nothing would ever happen. For example, imagine a person attempting to push a large box; not just a quick push, but constantly pushing it so that the box eventually moves along the floor whilst the person remains in contact and continues to apply the same force. Imagine this person applies 10N to the box. According to the 3rd law, the box will apply 10N back onto the person. This is what doesn't make sense, since the box and the person are applying equal forces upon each other, both of them would not move anywhere, even if it is a relatively light box and friction is negligible. A good analogy would be arm wrestling: if person A applies a force to the left and person B applies an equal force to the right, both their hands would remain in the middle and no one would win. But clearly this is not a problem in everyday experiences - things are able to move if a large enough force is applied. I can easily drag a suitcase along the floor despite it applying the same force in the opposite direction. But my question is, how? If all interacting objects are applying equal and opposite forces to each other, how is anything able to move? To be more specific, how are any two objects able to move together despite them applying opposite forces to each other? Surely there needs to be a resultant force? This is driving me crazy!