B. Garcia wrote at 2005-03-31 17:11:40 (-0800) > All of these arguments about if wheels turn left or right or things > roll left Vs. right when you're in a cart or whatever, is why I > suggested "forward rolling" and "backward rolling" - from the point > of view of someone looking at it from the side. If you take a > round log from a tree, and push it away along the ground it rolls > forward - clockwise to an observer looking at it. If you pull it > back to you the thing rolls backward, counter-clockwise to someone > looking at it. Uh, Barry, unless I'm missing something, that doesn't work. You're defining the motion according in terms of an observer looking at it from "the side", but there are two sides, and they'll see different things. If I'm rolling this log eastward, for example, an observer to the north will see it turning anticlockwise while an observer to the south will see it turning clockwise.