Absolutely not. All motion is relative. There is no reason at all for the ball to change its forward velocity (which is zero from the point of view of the train). No 'push' is needed to maintain motion, since from one point of view that condition isn't even moving.
This fact, first expressed clearly by Galileo and Descartes, is the starting point of Newtonian physics. It's sometimes called 'the principle of inertia' or 'Galilean relativity.' It's also maintained in modern relativity.
Mike W.
(published on 08/27/2008)
