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0 votes
4.3k views
in Physics by (69.2k points)

A man,sitting firmly over a rotating stool has his arms streched. If he folds his arms, the work done by the man is

(A) zero 

(B) positive 

(C) negative 

(D) may be positive or negative.

1 Answer

+1 vote
by (69.7k points)
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Best answer

Correct option: (B) positive

Explanation:

The kinetic energy is

But in this case, I f < I i

∴ Tf > Ti (Because angular momentum remains conserved)

But w = ΔT = Tf – Ti > 0

Hence, work done is positive.

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