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Physics · PYQ NEET UG 2025
हिन्दीThe Sun rotates around its centre once in \( 27 \) days. What will be the period of revolution if the Sun were to expand to twice its present radius without any external influence? Assume the Sun to be a sphere of uniform density.
Correct answer · Option 4
108 days
Explanation
By conservation of angular momentum, \( I_1 \omega_1 = I_2 \omega_2 \). Since \( I \propto M R^2 \) and \( \omega \propto \frac{1}{T} \), we get \( R_1^2 / T_1 = R_2^2 / T_2 \). With \( R_2 = 2R_1 \), \( T_2 = 4 T_1 = 4 \times 27 = 108 \) days.
