A gymnast on ice folds his arms while rotation. Which of the following statements is true?

Speed of rotation increases as friction decreases

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Rotational kinetic energy decreases because moment of inertia decreases

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Rotational kinetic energy increases as angular momentum remains conserved

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None of the above

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Solution

The correct option is C Rotational kinetic energy increases as angular momentum remains conserved
$K . E . = \frac{L^{2}}{2 I}$
$L$ remains constant and due to folding of arms $I$ decreases & K.E. increases.

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A gymnast on ice folds his arms while rotation. Which of the following statements is true?

The correct option is C Rotational kinetic energy increases as angular momentum remains conservedK.E.=L22I L remains constant and due to folding of arms I decreases & K.E. increases.

The correct option is C Rotational kinetic energy increases as angular momentum remains conserved
$K . E . = \frac{L^{2}}{2 I}$
$L$ remains constant and due to folding of arms $I$ decreases & K.E. increases.