NEET Physics Question - Rotational Motion

Assertion (A): If earth shrink (without change in mass) to half its present size, length of the day would become 6 hours.

Reason (R): As size of the earth changes its moment of inertia changes.

Both (A) & (R) are true and the (R) is the correct explanation of the (A)

Both (A) & (R) are true but the (R) is not the correct explanation of the (A)

(A) is true but (R) is false

Both (A) and (R) are false

Solution:

Assertion (A) is true; by conservation of angular momentum \(L = I\omega\), if the radius halves, moment of inertia (\(I \propto R^2\)) becomes one-fourth. Thus, angular velocity (\(omega\)) becomes four times, making day length \(24/4 = 6\text{ hours}\).

Reason (R) is true and explains A; moment of inertia depends on mass distribution and size.

Rankers Physics

Earth Shrinking and Day Length

Solution:

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