Question

Explain why: (a) A pencil will write on paper but not on glass (b) The handles of motor cycle are covered with a rubber sheet with spikes (c) The soles of our shoes wear out gradually. (d) Tyres of car wear out gradually

Answer 1

a) A  pencil may not write on a glass because glass surface is very smooth and has no friction where as paper has friction and pencil's lead easily settles on it.  

b)The rubber handles provide friction to the biker and protects them from metal with soft grip.  

c)Shoe's soul wear out with time because  of frequent use and secondly because of pressure. The rubbing and friction makes them worn out.  

d)Air pressure, friction and heat are the reasons tyres of cars wear out.

Answer 2

pencil will not write on glass because glass is a smooth surface and friction is less on smooth surfaces