My railroad teacher showed us his video, how rail tracks are replaced. There was this crane, which was on placing the tracks and after it lifted the track, it started wobbling and it looked so soft, but they are made of some kind of steel. How is this possible?
In: Physics
Stiffness of an object is the function of the thickness and length in the direction of loading. A rail is quite shallow given its length which makes it flop. Thick and short equal stiff (no flop); thin and log equal flexible (flop).
Steel is very strong but compared to many other materials it is very easy to bend. You might for example use steel wire in your bike lock because it is very strong which prevents it being cut but still very flexible allowing you to bend it through the wheel and frame in order to lock your bike. Or you might use a steel ruler which is very hard to damage or disform but can be bent around shapes unlike a plastic ruler which just breaks when you try to bend it. The steel rails is a bigger version of this. It is very strong so it does not break and also provides the train with a nice smooth slippery surface. However what keeps the rails in place is the sleepers and ballast. So when you lift a rail off the ground there is nothing preventing it from flopping around like a jelly worm.
Latest Answers