The moment of inertia of a door of mass `m`, length `2 l` and width `l` about its longer side is.

Options

A. `(11 ml^2)/(24)`
B. `(5 ml^2)/(24)`
C. `(m l^2)/(3)`
D. none of these

Answer

C

Explanation

( c) `I (about YY') = (m l^2)/(12)`
Using parallel axis theorem :
(about AD) `(m l^2)/(12) + (ml^2)/(4) = (ml^2)/(3)`.
.