Example: o
o
o
When a person is rotating with hands stretched, so the moment of inertia will be more because distribution of mass is far from the axis of rotation.
As the person brings his arms close to body, moment of inertia decreases because the mass is now distributed close to axis.
In this situation no external torque is applied, means angular momentum is conserved.
o Iω = constant. o
As I decrease, angular velocity ω