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A boy stands on a freely rotating platfo...

A boy stands on a freely rotating platform with his arms extended. Hisrotation speed is 0.3 rev/s, when he draws in, his speed increases to 0.5 rev/s, then.the ratio of his moments of inertia in these two cases will be

A

`3: 5

B

`5: 3

C

`9: 25

D

`25: 9

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