"Relative" energy ? Hi all, I have this quest : If a man jump from the earth surface to the h - height, we can calculate the work he's created, which equals to mgh (m : his weight, g : gravity acceleration). But if one considers a new frame which is mounted to the jumping man, he can calculate the energy the jumping man has created according to the new frame, then we can see he has pushed the earth to the distance h with a certain velocity. So, in the new frame, he has created certain energy which is very much bigger than mgh. Thanks for reading and any explanation.