[EricH]

Originally Posted by Adam Y.

Believe it or not the wheels on a train are cone shaped even though you can't tell by staring at them. I think they are shaped like that because otherwise the train would derail easily.

Physics--There's a reason for it (to keep the train on the track, in this case). I forget the name of the principle. Here's a quick demo of how it works: attach the bottoms of two styrofoam cups (you know, those little white ones that come in huge packages) together, set up two rulers/metersticks (or something similar) parallel to each other and roll the cups down from one end to the other. That's what keeps the trains on the track (the flanges are backup).