Q. The moment of inertia of a dumb-bell, consisting of point masses $m_{1} = 2.0$ kg and $m_{2} = 1.0$ kg, fixed to the ends of a rigid massless rod of length $L = 0.6$ m, about an axis passing through the centre of mass and perpendicular to its length, is
A) $0.72\ kg\ m^{2}$
B) $0.36\ kg\ m^{2}$
C) $0.27\ kg\ m^{2}$
D) $0.24\ kg\ m^{2}$
Explanation
(c) $I = m_{1}r_{1}^{2} + m_{2}r_{2}^{2} = 2(0.3)^{2} + 1(0.3)^{2} = 0.27\ kg\ m^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.