UPSC Prelims 2013 · Question 38 of 99

UPSC Prelims 2013 question on Ball Bearings Friction

Ball bearings are used in bicycles, cars, etc., because:

  1. The actual area of contact between the wheel and axle is increased
  2. The effective area of contact between the wheel and axle is increased
  3. The effective area of contact between the wheel and axle is reduced
  4. None of the above statements is correct
Show answer

Answer: C. The effective area of contact between the wheel and axle is reduced

Analysis

Ball bearings reduce friction by minimizing the effective area of contact between moving parts such as the wheel and axle. Instead of sliding friction, ball bearings convert motion into rolling friction, which is much smaller and allows smoother movement with less energy loss. Therefore, ball bearings are used to reduce friction and wear in machines and vehicles.

Extra UPSC info

Rolling friction is always smaller than sliding friction, which is why wheels and ball bearings improve efficiency.

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