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Question
The 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.
Options
100 days
105 days
115 days
108 days
MCQ
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Solution
108 days
Explanation:
In the absence of external torque, angular momentum is conserved.
I1ω1 = I2ω2
`(2/5 MR_1^2)((2pi)/(T_1)) = (2/5 MR_2^2)((2pi)/T_2)`
`T_2 = T_1((R_2)/(R_1))^2`
= `27 xx ((2R_1)/(R_1))^2`
= 27 × 4
= 108 days
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Conservation of Angular Momentum
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