Question

Which of the following methods can decrease the friction?

• A. Applying lubricants to machinery
• B. Applying powder on carrom board
• C. Making shoes with spikes
• D. Adding wheels in a car

Answer 1

Answer: (A), (B), (D)

The correct options are
A Applying lubricants to machinery
B Applying powder on carrom board
D Adding wheels in a car

Friction can be decreased by making the surface smooth. By applying lubricants to machinery and by applying powder on carrom boards, the surface is made smooth and hence, the friction decreases.
By adding wheels, sliding friction is changed to rolling friction. As rolling friction is less than sliding friction, the friction decreases.

Friction is increased by making the surface irregular. By adding spikes to shoes, the irregularities between the shoes and ground increases and hence, the friction between shoes and ground increases.