Question

Three rings each of mass $M$ and radius $R$ are arranged as shown in the figure. The moment of inertia of the system about $AB$ is:

• A. 3${MR}^2$
• B. $\frac{3}{2}M{R}^2$
• C. 5${MR}^2$
• D. $\frac{7}{2}{MR}^2$

Answer 1

The correct option is D $\frac{7}{2}{MR}^2$

$\begin{array}{c}\text{Moment of inertia about}AB\text{is}\\ {\left(\frac{m{R}^2}{2}\right)}_1+{(\frac{M{R}^2}{2}+M{R}^2)}_2+(\frac{M{R}^2}{2}+M{R}^2)3\\ =\frac{7}{2}M{R}^2\\ \text{Hence option}D\text{is correct}\end{array}$