Consider two uniform discs of the same thickness and different radii R_1= R and R_2=α R made of the same material. If the ratio of their moments of…

Consider two uniform discs of the same thickness and different radii $\displaystyle \mathrm{R}_1=\mathrm{R}$ and $\displaystyle \mathrm{R}_2=\alpha \mathrm{R}$ made of the same material. If the ratio of their moments of inertia $\displaystyle \mathrm{I}_1$ and $\displaystyle \mathrm{I}_2$, respectively, about their axes is $\displaystyle \mathrm{I}_1: \mathrm{I}_2=1: 16$ then the value of $\displaystyle \alpha$ is :