A uniform square plate has a small piece \(Q\) of an irregular shape removed and glued to the center of the plate leaving a hole behind in the figure. The moment of inertia about the \(\mathrm{z}\)-axis is then

    

1. increased
2. decreased
3. the same
4. changed in unpredicted manner
(b) Hint: The moment of inertia depends on mass distribution.
In the given diagrams, when the small piece Q removed and glued to the center of the plate, the mass comes closer to the z-axis, hence, the moment of inertia decreases.