Question

What makes the steps of foot over- bridges at railway stations to wear out slowly?

Answer 1

Friction between the soles of the shoes and stairs leads to the worn out steps of the foot over bridges in railway stations.

Answer 2

Friction makes the steps of foot "over-bridges" at railway stations to wear out slowly.

When walking in the railway station, the "friction" between the shoes and the floor help us to stop from slipping.  Necessary grip is provided between the sole and ground due to friction forward reaction is applied to the us. The friction usually opposes the motion called relative motion between the two surfaces of objects in contact. Friction force is acted opposite to the applied force. The only thing which makes the object to "speed up" or "slow down" is force.