Question

give example of any three situation where friction acts as an aid???

Answer 1

useful:-
1: it helps us to walk .
2: it helps us to run a vehicle .
harmful :-
1: it damages the shoe soles .
2: it damages the machinery parts of any machine  .
          i hope it helps..............................^_^ 

Answer 2

1 .For applying brakes in vehicle during emergency
2.Helps in writing on paper with a pen.
3.Helps in walking on ground or smooth surface