A large drum having radius R is spinning around its axis with angular velocity ω, as shown in figure. The minimum value of ω so that a body of mass M remains stuck to the inner wall of the drum, taking the coefficient of friction between the drum surface and mass M as μ, is: (a) √((2g)/(μ R)) (b) √((g)/(2μ R)) (c) √((μ g)/(R)) (d) √((g)/(μ R))

Answer: (d). Normal force from the wall: N = Mω² R (towards the axis). Friction holds the weight: μ Mω² R ≥ Mg. ωmin = √((g)/(μ R)) So the answer is (d).

A large drum having radius R is spinning around its axis with angular… | JEE Main 2026 (21 Jan, Shift 2)

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Level Road & Rotating Platform

A large drum having radius $R$ is spinning around its axis with angular velocity $\omega$ , as shown in figure. The minimum value of $\omega$ so that a body of mass $M$ remains stuck to the inner wall of the drum, taking the coefficient of friction between the drum surface and mass $M$ as $\mu$ , is:

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Answer: (d)

Normal force from the wall: $N = M\omega^2 R$ (towards the axis).
Friction holds the weight: $\mu M\omega^2 R \ge Mg$ .
$\omega_{min} = \sqrt{\frac{g}{\mu R}}$
So the answer is (d).

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