Ball bearings and friction reduction
Question
Ball bearings are used in bicycles, cars, etc., because (a) the actual area of contact between the wheel and axle is increased (b) the effective area of contact between the wheel and axle is increased (c) the effective area of contact between the wheel and axle is reduced (d) None of the above statements is correct
Options
the actual area of contact between the wheel and axle is increased
the effective area of contact between the wheel and axle is increased
the effective area of contact between the wheel and axle is reduced
None of the above statements is correct
Explanation
Ball bearings reduce friction by converting sliding friction into rolling friction. Rolling friction is much lower than sliding friction because the contact area is minimized (point contact for each ball rather than broad surface contact). Since friction = μ × N (where N is normal force), reducing contact area reduces the coefficient of friction and total friction force. Ball bearings achieve this by having spherical surfaces that touch at minimal points. Options (a) and (b) are incorrect—bearings reduce, not increase, effective contact area. The key principle is that rolling friction requires less force to maintain than sliding friction. > Friction principle: Ball bearings = Rolling friction (low) vs Sliding friction (high); Point contact << Surface contact.
Question details
Year
2013
Paper
GS Paper 1
Question
Q88
Subject
Science & Technology
Sub-topic
Physics - friction and mechanics
Type
Factual single
Difficulty
Medium
Nature
Static
Source hint
NCERT Physics - friction and motion
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