Question

The figure shows a thin metallic triangular sheet $ABC$. The mass of the sheet is $M$. The moment of inertia of the sheet about side $AC$ is

• A. $\frac{M{l}^2}{18}$
• B. $\frac{M{l}^2}{12}$
• C. $\frac{M{l}^2}{6}$
• D. $\frac{M{l}^2}{4}$

Answer 1

The correct option is C $\frac{M{l}^2}{6}$

ABC is a symmetric part of a square of side l.

M.I of a square bar of mass M and side l is $\frac{M}{12}(l^2+l^2)=\frac{2M{l}^2}{12}$

∴\therefore $M.I=\frac{M{l}^2}{6}$