Okay, this stems from a physics argument we had in class today; everyone in the arguement (my teacher included), seemed to think that we could stop the earths' rotation by walking in the opposite direction saying it was "common sense" however I argued that surely it would have no effect as the same force you use walking forward with your step is acted back upon you as you put your foot back on the ground, due to conservation of momentum? I know that while you're in the process of stepping (between leaving and landing) the rotation is messed. (similiar to shooting a bullet - forces you backwards, but lands in a wall which pushes the wall backward) i hope you can understand what i mean however i drew a quick diagram; excuse the poor diagram so, who was right? even my teacher seemed baffled by my attempts to explain it (perhaps he needed time to think, or indeed, he's right). at the time i was sure but since then i've begun to doubt my claims.