• # question_answer Three thin rods each of length L and mass M are placed along$X,Y,$and Z-axes in such a way that one end of each of the rods is at the origin. The moment of inertia of this system about Z-axis is: A) $~2\text{ }M{{L}^{2}}/3$             B) $~4\text{ }M{{L}^{2}}/3$C) $~5\text{ }M{{L}^{2}}/3$             D) $~M{{L}^{2}}/3$

${{I}_{2}}={{I}_{1}}+{{I}_{2}}+{{I}_{3}}=\frac{M{{L}^{2}}}{3}+\frac{M{{L}^{2}}}{3}+o=\frac{2M{{L}^{2}}}{3}$ This is because z-axis is passing through one end of each of two rods aligned along  and y-axes. Hence, the correction option is [a].