Question

A solid sphere is rotating in free space. If the radius of the sphere is increased keeping the mass same without applying any external force, which one of the following will not be affected?

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

Answer 1

The correct option is B Angular momentum

$I=\frac{2}{5}m{R}^2$ (For sphere)

$I\propto R^2$
$\therefore$ Moment of inertial will increase
$\to$ Angular moment will remain constant as net external torque is $zero$.