Question

Friction is necessity evil, why.

Answer 1

it causes wastage of energy
it wear out the rubbing surface
it generates heat,which harm machine

Answer 2

friction is a necessary evil because if there is no friction, you wouldn't be
- able to walk
- able to drive cars as they would slip on the road
- able to light a matchstick
- able to write on paper

But friction is also bad as
- generates heat: it can damage a moving machine
- wears out rubbing surfaces: the soles of your shoes wear out because of friction