The Train Problem

What keeps train wheels on a track? When a train rounds a bend, the outer wheels have to travel a further distance than the inner wheels, and therefore the outer wheels have to spin at a quicker rate to cover that distance than the inner wheels cover. The problem is that pairs of wheels on a train are connected by a solid metal axle, so the wheels can't spin at different rates. So, how does it work?

Richard Feynman explains.

Too soon?

Some Michael Jackson humour: CSI's take on it. Oh, Wikipedia.... This isn't funny, but its ironic.