Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Laws of Motion

Question:

A gramophone record is revolving with an angular velocity ω. A coin is placed at a distance r from the centre of the record. The static coefficient of friction is μ. The coin will revolve with the record if : 

Options:

\(r \geq \frac{\mu g}{\omega^2}\)

\(r = \mu g \omega^2\)

\(r < \frac{\omega^2}{\mu g}\)

\(r \geq \frac{\mu g}{\omega^2}\)

Correct Answer:

\(r \geq \frac{\mu g}{\omega^2}\)

Explanation:

\(\mu g \omega^2 \geq mr\omega^2\)

⇒ \(r \geq \frac{\mu g}{\omega^2}\)