How can trains move on rails? if the wheels are smooth and the rails are also smooth, how can it be enough friction for it to move?

Question

How can trains move on rails? if the wheels are smooth and the rails are also smooth, how can it be enough friction for it to move?

In: 2785

Answer 1

Because friction is only very low, but it is not zero. We actually want low friction to save energy.

Trams and trains generally carry sand to put on the tracks to increase friction temporarily (e.g. steep inclines in ice and snow, or emergency breaking).