Question

the stone of a hand flour grinder is provided with a handle near its rim.why?

Answer 1

Torque = force × perpendicular distance. By providing handle near rim the perpendicular distance between point of pivotion and point where force is applied, less force has to be applied to do work.

Answer 2

The handle is provided near its rim for providing external force in the hand flour grinder.

Explanation:

The stone in the hand flour grinder is provided with a handle to rotate the wheel of the grinder in a circular motion. This rotation by the handle will act as the external force along the perpendicular direction from the pivot and hence sin 90° = 1

So,

$\text{Moment of force} = \text{Force} \times \text{Perpendicular distance from the pivotal position}$

Thus to easily grind the flour with less force, the handle is provided near its rim.