A disc of mass $\text{'}\mathrm{m}\text{'}$ and radius $\text{'}\mathrm{R}\text{'}$ is rotating with angular speed ${\mathrm{\omega }}_0$ and speed zero as shown and then placed on a rough surface (coefficient of friction$=\mathrm{\mu }$) and left. Then,

Angular momentum of disc is conserved about the centre of mass.

Initially the force of friction is $\mathrm{\mu mg}$ leftwards.

Angular momentum of disc is conserved about the point of contact on the ground.

Initially the force of friction is $\mathrm{\mu mg}$ rightwards.