Question

Three solid spheres each of mass $P$ and radius $Q$ are arranged as shown in fig. The moment of inertia of the arrangement about $Y Y'$ axis

• A. $\frac{7}{5} P Q^{2}$
• B. $\frac{14}{5} P Q^{2}$
• C. $\frac{16}{5} P Q^{2}$
• D. $\frac{5}{14} P Q^{2}$

Answer 1

Answer: (C)

$I=\left(\frac{2}{5} m R^{2}\right)+\left(\frac{2}{5} m R^{2}+m R^{2}\right)+\left(\frac{2}{5} m R^{2}+m R^{2}\right)$
$=\frac{16}{5} m R^{2}$