Discuss conservation of angular momentum with example.

Explanation

(i) According to law of conservation of angular momentum, when no external torque acts on the body, the net angular momentum of a rotating rigid body remains constant.
i.e. If `tau = (dL)/(dt) = 0`, L = Constant
(ii) But L = `I omega`, So that,
`I omega` = Constant or `I alpha (1)/(omega)`
(iii) It shows that if the moment of inertia I increses, the angular velocity `omega` decreases and vice versa.
Example :
The ice dancer spins slowly when the hands are stretched out as this position increases moment of inertia and spis faster when the hands are brought close to the body as it decreases moment of inertia as shown in figure.

A diver while in air increases the number of somersaults by curling his body close, to decrease the moment of inertia moment of inertia as shown in figure.