Question

15. Explain the following:
(a) Why are the worn-out tyres discarded?
(b) Why do carom coins move faster on the carom board w
carom coins move faster on the carom board when dusted with talcum powder?
(C) Why is the surface of a conveyor belt made rough:
(d) Why is a sewing machine often oiled?
(e) Why do new automobile tyres have deep grooves!
(f) Why does a ball rolling on the ground slow down?
(g) Why is a boat or an aeroplane given special shape?​

Answer 1

Answer:

A small quantity of fine powder in a wooden surface of floor reduce friction.

That is why a small quantity of talcum powder is applied on talcum powder.

Graphite powder is used in machines to reduce friction.

Answer 2

Answer:

a) the worn out tyres are discarded because

the tyres lose there grip over the road and it may lead to an accident

b) carrom coins move faster on carrom board because there is less friction in comparison with floor

c) to increase friction

d) so that the ball bearing do not get damaged and prevents sewing machine to get heated up

e) to have firm grip over the road

f) due to frictional force

g) because of aerodynamics and cause less friction