Question

A square plates of mass $120g$ and edge $5.0cm$ rotates about one of the edge. It has a uniform an acceleration of $0.2rad/s^2$, what torque acts on the plate?

Answer 1

A square plate of mass $120gm$ and edge $5cm$ rotates about one of the edge.

Let take a small area of the square of width $dx$ and length $a$ which is at a distance $x$ from the axis of rotation.

We know that the moment of inertia of the square plate about one of the edge is $I=\frac{m{a}^2}{3}=\frac{0.12kg\times (.05{)}^2{m}^2}{3}={10}^{-4}kg{m}^2$

acceleration is given as $\alpha =0.2rad/s^2$

so torque experienced is given by:

$\tau =I\alpha$

$=2\times {10}^{-5}Newton-meter$