Question

Two masses of $6kg$ and $3kg$ are connected by a light rod of $12cm$. If size of masses is negligible, then moment of inertia of system is minimum about an axis through a point which is

• A. $6cm$ from $6kg$
• B. $2cm$ from $6kg$
• C. $4cm$ from $6kg$
• D. $8cm$ from $6kg$

Answer 1

The correct option is C $4cm$ from $6kg$

M.I. of system is minimum about center of mass of system.

$M_1{X}_1=M_2{X}_2$
$6X=3(12-X)$
$2X=12-X$
$X=4cm$