Question

Of the following statements choose the correct combination that helps reduce friction:
A) Grease is used to reduce friction in bicycle chain
B) Ball bearings are used to reduced friction in a fan
C) Oil can be used to increase friction in a car engine
D) Talc can be used to reduce friction when an object is sliding on a surface.

• A. A, B, D
• B. A, C, D
• C. B, C, D
• D. A, B, C

Answer 1

The correct option is A

A, B, D

Oil is used as a lubricant in order to reduce the roughness of surfaces in contact. Since option C negates this property, it is incorrect.
From the rest of the statements, A and D are lubricants, which is used to make the surface slippery. And ball bearings reduce friction by rolling as rolling friction has a very less coefficinet of friction than sliding friction. So, as stated in the statements, they reduce friction.
So, correct combination : A,B,D.