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The Principle

A gymnast tak...

Question

A gymnast takes turns with her arms & legs stretched. When she pulls her arms & legs in

A

The angular velocity decreases

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B

The moment of inertia decreases

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C

The angular velocity stays constant

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D

The angular momentum increases

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Solution

The correct option is B The moment of inertia decreases
Since no external torque act on gymnast, so angular momentum $(L = I ω)$ is conserved. After pulling her arms & legs, the angular velocity increases but moment of inertia of gymnast, decreases in, such a way that angular momentum remains constant.

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