Railroad Trains, Part 2 Wheels and Friction

Wheels and Friction

We first talked about experiments they have done with cars rolling down ramps and how it is much easier for the toy car to roll down a smooth ramp than a rough surface. We talked about the difference between carrying a load of books on foot,  in a wagon over a graveled surface and in a wagon over a smooth surface. Then we discussed the loads that railroad trains carried and how they needed the track to be a very smooth road for the train wheels in order to reduce the friction. Not only are the steel rails smooth and clean, but the land on which the railroad is built is levelled. When building a railroad the engineers often encountered such obstacles as mountains and gullies. They either had to go around it or build a tunnel or bridge.

In order to stay on the rails, which are thin, train wheels have flanges on the side.