A circular disc is rotating with angular velocity $\omega$. If a man standing at the edge of the disc walks towards its centre then the angular velocity of the disc will

When no external force acts on a body its angular moment remains conserved. From law of conservation of angular momentum, we have $J=l \omega=$ constant where $/$ is moment of inertia of the body and $\omega$ is angular velocity. Also $I=\frac{1}{2} M R^2$ (for disc) where $M$ is mass and $R$ is radius of disc. $J=\frac{1}{2} M R^2 \omega=$ constant Since, man moves towards the centre of the disc, distance of mass distribution $R$ decreases hence, $\omega$ increases.