Same chapter3 marksDifficulty: Medium
Find the moment of inertia of a thin uniform rod of mass M and length L about an axis through its centre and perpendicular to it, and about one end.
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3 marksDifficulty: Medium
Why does an ice skater spin faster on drawing the arms inwards?
Original Khojo Papers practice question — not from a past board paper.
Answer
No external torque acts on the skater, so the angular momentum Iω is conserved. Drawing the arms in reduces the moment of inertia, so the angular velocity must increase to keep the product constant.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The kinetic energy increases, the extra energy coming from the work done in pulling the arms in.
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