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Adam Boutin asked the Naked Scientists: Hello I have a Science question. Newton's Third Law of Motion states that for every action there is an equal and opposite reaction. According to that, when I stand on the ground and jump up, away from the Earth, then the Earth must also move an infinitesimal distance away from me. Is this really true in practice?I listen to your podcast while I am doing my own science!AdamBoston, Massachusetts U.S.What do you think?
But LeeE - but this doesn't mean that the Earth doesn't all move, albeit by a miniscule amount, surely?Chris
The whole Earth doesn't need to move if just moving a small part of it will suffice. If you want to look at it as a rigid-body problem though, then the Earth moves away from you when you jump up in the air but then starts moving towards you, just as you start moving towards it, as you come down again. In this case, neither of you is stationary while you are in the air.