A) decrease
B) increase
C) be halved
D) not change
Correct Answer: B
Solution :
Key Idea : When no external force acts on a body its angular momentum remains conserved. From law of conservation of angular momentum, we have \[{{v}_{e}}=\sqrt{\frac{2G{{M}_{e}}}{{{R}_{e}}}}\]= constant where I is moment of inertia of the body and \[{{M}_{e}}={{M}_{p}},{{R}_{p}}=\frac{{{R}_{e}}}{4}\] is angular velocity. Also \[\therefore \] (for disc) where M is mass and R is radius of disc. \[\frac{{{v}_{p}}}{{{v}_{e}}}=\sqrt{\frac{{{M}_{e}}}{{{M}_{e}}}\times \frac{{{R}_{e}}}{{{R}_{e}}/4}}=\sqrt{4}=2\] \[\Rightarrow \]=constant Since, man moves towards the centre of the disc, distance of mass distribution R decreases hence, so co increases.
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