Which one of the following statements is incorrect ?

1. Rolling friction is smaller than sliding friction.

2. Frictional force opposes the relative motion.

3. Limiting value of static friction is directly proportional to normal reaction.

4. Coefficient of sliding friction has dimensions of length.

Doubtly Asked 30 Oct 2026 NEET UG 2018 Practice test neet Save WhatsApp Report

1 answer

Best answer

Answer: 4. Coefficient of sliding friction has dimensions of length.

Check each statement.

Rolling friction is smaller than sliding friction: true.
Friction opposes relative motion: true.
Limiting static friction \(f_s=\mu_sN\), proportional to normal reaction: true.
\(\mu=f/N\) is a ratio of two forces, so it is dimensionless, not a length. This statement is incorrect.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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