here is ur answer
<> friction is called the necessary evil, that means it is sometimes necessary and also sometimes evil, that is a disadvantage.
<> friction helps us to walk , with out friction we will slide and there is no stopping we will continue sliding for our whole life.
where does this friction exsist?
<> on everything there is friction there is no substance which is friction less. there are small irregularities on every substance so when slide over one substance on other these irregularities get caught up with each other, hence we need to is energy to overcome that friction. hence our energy us wasted.
<> friction causes wear and tear. this applies in the case of the shoe. when the irregularities of our shoe and the surface caught up it causes the shoe wear and tear and also because of the heat produced by frictional force causes wear and tear.
do the sole of our shoe will be of no use when we walk alot on the surface and alot of friction us applied.
