JEE PHYSICS MCQ: GRAVITATION

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Assertion: If the earth expands in size without any change in mass, the length of the day would increase.
Reason: The rotation of earth about its axis follows the law of conservation of angular momentum.

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Correct option: A

Assertion is true, Reason is true; Reason is the correct explanation of Assertion

Option A is correct because if the Earth expands without mass change, its moment of inertia increases, leading to a decrease in angular velocity and thus an increase in the length of the day, due to conservation of angular momentum.

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