Question

Frictional force in a ceiling fan is reduced by using .......................

• A. Reduced air resistance
• B. Ball bearings
• C. Both (A) and (B)
• D. None of the above

Answer 1

Answer: (B)

Ball bearings

When one body rolls over the surface of another body the resistance of its motion is called rolling friction. Rolling friction reduces friction. It is easier to slide then to roll and hence sliding friction is less than rolling friction.

Since rolling friction is smaller than sliding friction , sliding is replaced in most machines by rolling by using ball bearings. Thus ball bearings are used between axle and the hub of a fan to reduce the friction force.