Home › NEET UG › Physics › System of Particles and Rotational Motion › An ice skater spinning with arms outstretched pu…
An ice skater spinning with arms outstretched pulls her arms in. Her angular speed:
ADecreases
BBecomes zero
CStays the same
DIncreases
Answer & Solution
Correct answer: D. Increases
1. External torque on the skater about the spin axis is negligible.
2. Angular momentum L = I ω is conserved.
3. Pulling arms in REDUCES I (mass moves closer to the spin axis).
4. Therefore ω must INCREASE to keep L constant.
5. KE = ½ I ω² actually INCREASES — work done by the skater's muscles.
_Source: NCERT Class 11 Physics Ch 6 §6.10 (illustrative example)_
Related questions
The radius of gyration k of a body about an axis is defined so that:Two bodies have the same angular momentum L. The one with the LARGER moment of inertia hasA wheel rolls without slipping with the centre of mass having velocity v. The instantaneouA solid sphere of mass M and radius R has moment of inertia about a diameter:A flywheel of moment of inertia 2 kg m² rotates at 60 rpm. The torque required to bring itTotal kinetic energy of a body rolling without slipping is:A solid disc and a hollow ring of the same mass and radius roll without slipping down the If the net external torque on a system is zero, then: