Question

In a metallic triangular sheet $ ABC $ , $ AB = BC = l $ . If $ M $ is mass of sheet, what is the moment of inertia about $ AC $ ?

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

Answer 1

Answer: (B)

Moment of inertia of triangular sheet $A B C$ about $A C=\frac{1}{2}$ moment of inertia of square $A B C D$ about $A C$

$=\frac{1}{2}(2 \,M) \frac{l^{2}}{12}=\frac{M l^{2}}{12}$