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# A man spinning in free space changes of his body e.g by spreading his arms and curling up. By doing this, he can change his 1) moment of inertia 2) angular momentum 3) angular velocity 4) rotational kinetic energy in this Which of the following is correct?

a) 1,2 and 3

b) 1,3 and 4

c) 2,3 and 4

d) 1,2 and 4

## 2 Answers

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A)
conceptual one

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A)
When a man spinning changes his position of body by spreading arms or curling up his angular momentum does not change as there is no external torque, by conservation of angular momentum. But his moment of inertia, angular velocity changes.
L=constant" role="presentation" style="position: relative;">L=constantL=constantL = constant
I1w1=I2w2" role="presentation" style="position: relative;">I1w1=I2w2I1w1=I2w2I_1 w_1 = I_2 w_2
Since I" role="presentation" style="position: relative;">III changes his rotational kinetic energy also change.
1, 3 and 4 are correct.
Hence (b) option is correct.