An ice-skater can greatly increase his speed of rotation in a spin by drawing in his limbs towards the spin axis. This is because:
Correct answer: A. His moment of inertia decreases
- A. His moment of inertia decreases
- B. His angular momentum increases
- C. His potential energy decreases
- D. His centre of gravity changes
Explanation
We make use of the principle of conservation of angular momentum for this question. When the ice skater pulls in their limbs during a spin, their moment of inertia decreases due to the redistribution of mass. According to the conservation of angular momentum, as the moment of inertia decreases, the angular velocity (spin speed) must increase to maintain the same angular momentum. This principle is analogous to a figure skater spinning faster when pulling their arms and legs closer to their body.
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About Gravitation
Newton’s law of universal gravitation relates the force between masses to their masses and separation, while gravitational field strength explains weight and orbital motion. The topic covers satellite velocity and period, escape ideas, weightlessness in free fall, and artificial gravity, which differs from ordinary gravitational attraction.
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