Question

(a) Ball-bearings are used in machines.
(b) Tyres of the vehicles need to be changed regularly.
(c) Machines parts are frequently oiled or greased.
(d) Sport cars, aeroplanes and boats are designed to have a streamlined shape.
(e) Metal chains are wrapped on tyres when they run on icy roads.
(f) Rollers are used for transporting luggage.​

Answer 1

Answer:

Explanation:

a. Ball bearings reduces the friction and thus efficiency of machines increases thats why used in machines.

b. Tyres need to be regularly changed because they get wear and tear due to friction so to avoid accidents it is done.

c.  Machine parts are oiled or greased because of their smooth functioning.

d. sports cars boats have streamlined shapes to reduce the fluid friction.

e. Metal chains are wrapped on tyres when they run on icy roads to increase friction so that brakes can be easily applied.

f. Rollers are used for transporting luggage because of rolling friction as it is easier to roll a body than to slide it.

Answer 2

Answer:

Hope it's helpful for you