In certain cases, we need friction while in certain others we have to reduce friction. It means friction has some advantages as well as disadvantages. It is difficult to walk on ice because of less friction. A nail stays in the wood because of friction. Similarly, we can tie a knot because of this force. A horse will not be able to pull a wagon unless friction furnishes him a secure foot-hold.

Friction causes energy loss and reduces the efficiency of machines. Friction causes rapid wear and tear.

In short, we can say that friction is necessary for everyday activities. Thus, the statement that “friction is necessary evil” is correct.

The wheel would not recoil on pushing it if there would be no friction between the wheel and the ground. Thus, friction is desirable for wheels to roll over a surface.