A rod P Q of mass M and length L is hinged at end P . The rod is kept horizontal by a massless string tied to point Q as shown in the figure. When string is cut, the initial angular acceleration of the rod is

Question

A rod P Q of mass M and length L is hinged at end P . The rod is kept horizontal by a massless string tied to point Q as shown in the figure. When string is cut, the initial angular acceleration of the rod is, 3 g 2 L, g L, 2 g L, 2 g 2 L

MARKS App · Accepted Answer

Torque on the rod = Moment of weight of the rod about P . τ = M g L 2 ..... (i) Moment of inertia of the rod about P I = M L 3 3 ..... (ii) As, τ = I α From Eqs. (i) and (ii), we get M g L 2 = M L 2 3 α ⇒ α = 3 g 2 L

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