This time’s question is a friend’s inquiry. He recently came across a railroad crossing. For those of us who have spent time in smaller towns in this country, railroads through the middle of the road are rather common. Now he was under the impression that the steel rails have some kind of grooves into which the wheels of the train fit. But when he saw one of these rail crossings recently, he noticed that the road and the rails were at the exact same level, with no space between them- there is no space for the train wheels to fit around the rails- no groove mechanism.
Now as someone who has seen a lot of drama films, the fairly common scene of a fast moving train breaking hard and sparkles flying besides the wheels, is quite strongly etched in my memory (like this one from Hugo)- The groove idea never crossed my mind. I always thought that the wheels moved on the rails. But my friend’s question made me think- why don’t trains slip from the rails? This might sound silly to some. But it really isn’t obvious to me. Of course, friction is at play here. But that isn’t a satisfactory hint at all. Trains with the speed they move at, ought to slip on something as smooth as steel rails. But they don’t. Why?
If you know the answer, and it is very obvious to you, please don’t use it as an excuse to not answer. Enlighten the rest of us.