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A child is standing with folded hands at...

A child is standing with folded hands at the center of a platform rotating about its central axis. The kinetic energy of the system is `K`. The child now stretches his arms so that the moment of inertia of the system doubles. The kinetic energy of the system now is

A

2 K

B

`K/2`

C

`K/4`

D

4 K

Text Solution

Verified by Experts

The correct Answer is:
B
`Iomega= 2Iomega. implies omega.=omega/2`
`K =1/2Iomega^2`
`K. =1/2 xx 2I xx omega^(.2) = (Iomega^2)/4 = K/4`
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