Answer: 6 hours.
- A 6 hours
- B 24 hours
- C 12 hours
- D 3 hours
Correct answer: A. 6 hours
Explanation: I = (2/5)MR². If R halves, I becomes (1/4) of original. L = Iω is conserved, so ω quadruples and T = 24/4 = 6 hours.
Torque about axis O equals the force F multiplied by the perpendicular distance r⊥ from the axis to the line of action of the force, producing rotation.
Concept context
Moment of inertia, torque, angular momentum, rolling motion. Very high JEE weightage.
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