A solid sphere is rotating freely about its symmetric axis in free space. The radius of the sphere is…

A solid sphere is rotating freely about its symmetric axis in free space. The radius of the sphere is increased keeping its mass same. Which of the following physical quantities would remain constant for the sphere?
  1. Rotational kinetic energy
  2. Moment of inertia
  3. Angular velocity
  4. Angular momentum

Solution

∵τext =dL→dt
So, when τ ext  =0⇒  d L → dt =0
⇒  L → = constant
So angular momentum remains constant.

Asked in: NEET 2018

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