A solid sphere is rotating freely about its symmetry 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?

Options

A. Rotational kinetic energy
B. Moment of inertia
C. Angular velocity
D. Angular momentum

Answer

D

Explanation

Net external torque is defined as rate of change of angular momentum.
`vectau_(ext)=(dvecL)/(dt)`
In given situation no external torque acts on the system.
`vectau_(ext)=0`
`(dvecL)/(dt)=0`
So, `vecL`=constant
So direction and magnitude of angular momentum remains constant.
Hence option (d) is correct.