Question

Arrange the given materials in the increasing order of the frictional force provided by them when a brick slides over their surface.

• A. Concrete
• B. Wooden floor
• C. Metal
• D. Glass

Answer 1

Friction depends on the irregularities or roughness of a surface. An object will face the maximum resistance on a surface with maximum friction, i.e., a surface with maximum irregularities or roughness. Therefore, arranging the surfaces in the increasing order of their roughness will give us the increasing order of the frictional force provided by them.
Hence, the order of increasing frictional force is as follows:
Glass < Metal < Wooden floor < Concrete