Give two examples where friction is (a) Useful (b) A nuisance.
Advantages of friction:-
1.Friction helps us in walking.Without friction we would slip as soon as we try to walk.
2.Friction helps us in writing with pen,pencil etc.
Disadvantages of friction:-
1.It makes the machines in the factories or car engines overheated.
2.Friction wears out the soles of our shoes.