Question

By which of the following ways we can maximise the torque of a force applied to a rotating object?
I. Maximise the magnitude of the applied force.
II. Reduce the distance of a point from the axis of rotation at which force is applied.
III. Apply the force perpendicular to the displacement vector between the axis of rotation and the point of applied force.

• A. I only
• B. II only
• C. I and II only
• D. I and III only
• E. I, II, and III

Answer 1

The correct option is D I and III only

The torque of a force is given by

$\tau =rF\sin \theta$

therefore $\tau$ can be maximised if we -- maximise the force $F$

--maximise the $r$

--maximise the $\sin \theta$, maximum value of $\sin \theta$ is $1$ i.e.$\sin \theta =1=\sin 90$ or $\theta =90$ it means we apply the force perpendicular to the displacement vector between axis of rotation and point of applied force.