Physics - Rotation Question with Solution | TestHub

The angular momentum of the system is conserved as there are no external torques acting on the system. Initial moment of inertia $I_i=I_{platform}+I_{person,center}=\frac{1}{2}M{R}^2+0=\frac{1}{2}M{R}^2$. Final moment of inertia $I_f=I_{platform}+I_{person,edge}=\frac{1}{2}M{R}^2+m{R}^2=(\frac{1}{2}M+m)R^2$. By conservation of angular momentum, $I_i{\omega }_0=I_f{\omega }_f$.$\frac{1}{2}M{R}^2{\omega }_0=(\frac{1}{2}M+m)R^2{\omega }_f$.${\omega }_f=\frac{\frac{1}{2}M}{\frac{1}{2}M+m}{\omega }_0=\frac{M}{M+2m}{\omega }_0$