Question:
Calculate the torque on the square plate of the previous problem if it rotates about a diagonal with the same angular acceleration.
Solution:
M.I. of square plate about its diagonal
$$
\begin{aligned}
&\mathrm{I}=\frac{m a^{2}}{12} \\
&\tau=I \alpha \\
&=\frac{(0.12)(0.05)^{2}}{12}(0.2) \\
&=0.5 \times 10^{-5} \mathrm{~N}-\mathrm{m}
\end{aligned}
$$