Question:
Is there a force of friction between the wheels of a moving train and iron rails? If yes, name the type of friction. If an air cushion can be
introduced between the wheel and the rail, what effect will it have on the friction?
Solution:
Yes, there is always a force of friction between the wheels of a moving train and iron rails. The name of this friction is rolling friction, since the wheels
are rolling on the track.
On introducing air cushion, the frictional force becomes less, since there is no contact between rails and wheels.