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Hi I have a quick question. I know this may be a common question. If N3L states that there's an equal and opposite force, why do things still move?
I have read up a lot and this is my understanding. If a finger exerts a force on a box, then box will move/accelerate. At the same time, box exerts an equal force on the finger. The motion of box(assuming no friction) is affected only by force from the finger. (I think the term is System = box). Thus, the reaction force from box only affects the motion of finger and has no relevance to the motion of the box.
However, I came to this question. If the reaction force from the box on the finger is equal to the force from the finger to the box, then there must be some other kind of force on the finger that is opposite to the reaction force and greater, since the finger is accelerating/moving. What is that force?