Question

Find the moment of inertia of an equilateral triangular lamina of mass $1\text{kg}$ and having sides $3\text{m}$ about the axis passing through its centre of mass and perpendicular to the plane of triangular lamina.

• A. $0.75{\text{kg-m}}^2$
• B. $1.5{\text{kg-m}}^2$
• C. $1{\text{kg-m}}^2$
• D. $3{\text{kg-m}}^2$

Answer 1

The correct option is A $0.75{\text{kg-m}}^2$


Given:
Sides of the equilateral triangular lamina $;a=3\text{m}$
Mass of triangular lamina $;m=1\text{kg}$

M.O.I of equilateral tringular lamina about the axis passing through its centre of mass;
$I_{com}=\frac{m{a}^2}{12}$
$=\frac{1\times 3^2}{12}{\text{kg-m}}^2$
$=0.75{\text{kg-m}}^2$