Question

A brick is pulled with the help of a spring balance on the following surfaces. Sort these surfaces in the increasing order of the reading shown by the spring balance.

Answer 1

When a brick is pulled on the given surfaces, the smoothest surface will offer the least friction and the spring balance will show minimum reading. Similarly, the spring balance reading will be maximum on the roughest surface as it offers maximum friction.
The spring balance will show maximum reading on the cloth and the minimum reading on the glass surface. So the correct order will be:
Glass < Metal < Wood < Cloth