Conservation Of Angular Momentum
A skater decreases moment of inertia from 4 to 1 kg·m². Initial ω = 3 rad/s. Final ω?
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About This Question
- Subject
- physics
- Chapter
- rotational motion
- Topic
- conservation of angular momentum
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
12 rad/s
- Conservation Law: If no external torque acts on a system, the total angular momentum L remains constant.
- Mathematical Form: L=I1ω1=I2ω2.
- Scenario Analysis: By pulling her arms in, the skater decreases I. To keep L constant, ω must increase.
- Calculation:
- 4 kg\cdotpm2×3 rad/s=1 kg\cdotpm2×ω2
- 12=1×ω2⟹ω2=12 rad/s.
- Significance: This explains how spinning objects speed up when they become more compact.
This medium difficulty physics question is from the chapter rotational motion, covering the topic of conservation of angular momentum. It appeared in the 2025 exam.
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