Question

Give four situations each where friction is necessary and where it is not necessary.

Answer 1

Necessary:
1) While driving a car, friction between the tyres and the road is necessary.
2) Friction between your shoes and the floor helps you walk.
3) Friction between a piece of chalk and the blackboard aids in writing on it.
4) Friction helps you to grip the string of a kite while flying it.

Not Necessary:
1) Inside moving parts of a machine, where unnecessary friction can generate unwanted heat.
2) Friction causes wearing of machine parts over time.
3) It is because of friction that the sole of your shoes wear out.
4) Due to friction, noise is also produced in machines, like in a sewing machine.