When is friction un useful?

Answer 1

i wonder if you mean when is friction not useful ?

well; it is useful when you require a surface to hold onto another item .

such as the clutch and brake components in a car.

a clutch depends on the friction of the metal surface of the clutch plate to drag against another surface to disengage the drive mechanism .

A brake system needs the friction between fibre brake shoes and metal case to slow down a car-- vehicle .

this is useful.

however , in some areas of a car there are parts that require very little friction,

such as wheel bearing and inlet and exhaust timing valves which control the operation of fuel ignition timing within engine compartment .

these component's have a limited amount of friction but depend upon a coolant such as lubrication oil to ease this friction - action .

with an increase in thickness -- measurements the clearances will become less and hence the friction will increase to cause excess heat production .

this will cause undesirable heat effect, and expansion and wear and quite likely overheating .

( undesirable result of friction )

Answer 2

Friction is unuseful when trying to minimize energy loss in machines or when attempting to achieve low resistance for moving parts. In cases such as reducing wear and tear on components or conserving energy in systems, friction can be a hindrance.