Q. Three 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 rod is at the origin. The moment of inertia of the system about $Z$-axis is
A) $\frac{ML^{2}}{3}$
B) $\frac{2ML^{2}}{3}$
C) $\frac{3ML^{2}}{2}$
D) $\frac{2ML^{2}}{12}$
Explanation
(b) Moment of inertia of a rod about one end $= \frac{ML^{2}}{3}$
As, $I = I_{1} + I_{2} + I_{3}$
$\therefore\ \ I = 0 + \frac{ML^{2}}{3} + \frac{ML^{2}}{3} = \frac{2ML^{2}}{3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.