Question

Write the expression for the torque of a force about a given axis of rotation.

Answer 1

1. The turning effect of a force is called moment of forces or torque.
2. It is measured by the product of the force and the perpendicular distance of the line of action of force and axis of rotation.
3. Thus, Torque= force × (perpendicular distance from the axis of rotation).
   $$\begin{gathered} \zeta =F\times r=mar \\ \zeta =m{r}^2\alpha (a=r\alpha ) \\ \zeta =I\alpha where,I=m{r}^2 \end{gathered}$$

$I$ is the moment of inertia and $\alpha$ is angular acceleration.