Question

The moment of inertia of a circular disc about an axis passing through its centre and normal to its plane is $50kg{m}^2$. Then its moment of inertia about a diameter is

• A. $100kg{m}^2$
• B. $200kg{m}^2$
• C. $10kg{m}^2$
• D. $25kg{m}^2$

Answer 1

The correct option is D $25kg{m}^2$

$\begin{array}{c}\text{Given MOI Of disc about an axis passing through its}\\ \text{centre and normal to its plane is}{I}^{\prime }=50{kgm}^2\end{array}$

$\begin{array}{c}\text{we know that}{I}^{\prime }=\frac{m{R}^2}{2}\\ \text{weknow that}\\ \text{MOI about diameter}=\frac{m{R}^2}{4}=\frac{I}{2}\\ =25{kgm}^2\end{array}$