Q. The moment of inertia of a door of mass $m$, length $2 l$ and width $l$ about its longer side is
System of Particles and Rotational Motion
Solution:
$I\left(\right.$ about $\left.Y Y^{\prime}\right)=\frac{m l^{2}}{12}$
Using parallel axis theorem:
(about AD) $\frac{m l^{2}}{12}+\frac{m l^{2}}{4}=\frac{m l^{2}}{3}$
