Question
A hot solid sphere is rotating about a diameter at an angular velocity $\omega_0$. If it cools so that its radius reduces to $\frac{1}{\eta}$ of its original value, its angular velocity becomes .............
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Answer
(d)
Angular momentum will be conserved
$\frac{2}{5} m r^2 \omega_0=\frac{2}{5} m\left(\frac{r}{\eta}\right)^2 \omega^{\prime}$
$\omega^{\prime}=\eta^2 \omega_0$
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