A man, holding a weight in each hand, stands at the center of a horizontal frictionless rotating turntable. The effect of the weights is to double the rotational inertia of the system. As he is rotating, the man opens his hands and drops the two weights. They fall outside the turntable. Then:

A. his angular velocity doublesB. his angular velocity remains about the sameC. his angular velocity is halvedD. the direction of his angular momentum vector changesE. his rotational kinetic energy increases

Question

Physics

Alfonso Pope

21 May, 10:34

A man, holding a weight in each hand, stands at the center of a horizontal frictionless rotating turntable. The effect of the weights is to double the rotational inertia of the system. As he is rotating, the man opens his hands and drops the two weights. They fall outside the turntable. Then:

A. his angular velocity doublesB. his angular velocity remains about the sameC. his angular velocity is halvedD. the direction of his angular momentum vector changesE. his rotational kinetic energy increases

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Answers (1)

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Kissy · Answer 1

Explanation:CE

Let after the fall of weight from hands, the moment of inertia reduces from 2I to I. Since no external torque is acting on the system, angular momentum will be conserved.

I₁ ω₁ = I₂ ω₂

2I ω₁ = I ω₂

2ω₁ = ω₂

So, angular velocity will be doubled.

Option A is correct.