Physics - Rotation Question with Solution | TestHub

Let the mass of the disc and the ring be $M$ and their radii be $R$.

The moment of inertia of the disc is $I_d=\frac{1}{2}M{R}^2$.

The moment of inertia of the ring is $I_r=M{R}^2$.

Since $I_d<I_r$, the angular acceleration $\alpha =\frac{\tau }{I}$ will be greater for the disc for the same applied torque $\tau$.

Angular frequency is given by $\omega ={\omega }_0+\alpha t$. Assuming both start from rest, $\omega =\alpha t$.

Since ${\alpha }_d>{\alpha }_r$, it follows that ${\omega }_d>{\omega }_r$.

Therefore, the disc will rotate with greater angular frequency.

Answer: the disc will rotate with greater angular frequency.