My professor today stated that if a ball was to fall a certain height, then the work done by gravity on the ball would equal the work done by the ball's equal and opposite gravitational pull. By W=F*d, this means that the earth must travel the same distance as the ball. So if the ball falls 300 meters, the earth would eventually rise 300 meters in the direction of the ball's gravitational pull? My professor seems to not be too with it, and he has said a lot of things that didn't sit well today (this is only the second day of class). can you please give me your input on this particular matter?