Question

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

Answer 1

$Torque=I^{\prime }a$

$=[I+M{\left(\frac{a}{2}\right)}^2]a$

$=[\frac{M{a}^2}{12}+\frac{M{a}^2}{4}]a$

$=\frac{M{a}^2}{3}a$

$=\frac{0.12\times {0.05}^2}{3}\times 0.2$

$=2\times {10}^{-5}Nm$