Perpendicular Axis — SquareMediumQuestion 30329
Question
For a square lamina (side a, mass M) about an axis through centre, in the plane, I_x = Ma²/12. Moment of inertia about axis through centre perpendicular to lamina is:
- AMa²/12
- BMa²/6Correct
- CMa²/3
- DMa²/4
Correct answer
Ma²/6
Explanation
By symmetry I_x = I_y = Ma²/12. By perpendicular axis theorem: I_z = I_x + I_y = Ma²/12 + Ma²/12 = Ma²/6.