Question

Point masses $1,2,3$ and $4kg$ are lying at the points $(0,0,0)$, $(2,0,0)$, $(0,3,0)$ and $(-2,-2,0)$ respectively. The moment of inertia of this system about x-axis will be:

• A. $43kg-m^2$
• B. $34kg-m^2$
• C. $27kg-m^2$
• D. $72kg-m^2$

Answer 1

The correct option is A $43kg-m^2$

Moment of inertia about x axis, $I_x=I_A+I_B+I_C+I_D$

$I_x=0+0+3\times 3^2+4\times 2^2$

$⟹I_x=43kg{m}^2$