State one way to decrease the moment of a given force about a given axis of rotation.

Hint: Moment of force - the product of the perpendicular distance from the axis to the point of application of the force and the component of the force perpendicular to the line of the distance and in a plane perpendicular to the axis.

Complete step-by-step solution:
The moment of a given force a couple of given axis of rotation are often decreased by decreasing the perpendicular distance of force from the axis of rotation.
Moment of force a couple of given axes = Force × perpendicular distance of force from the axis of rotation.
The turning effect produced by a force on a rigid body of a couple of points, pivot or fulcrum is known as the moment of force or torque. It’s measured by the merchandise of force and thus the perpendicular distance of the pivot from the road of action of force.
To open the door, push with as big a force as possible, and as far as possible from the pivot – at the other fringe of the door, i.e., that's why the door handle is fitted there. To possess a huge turning effect, the person must push hard at right angles to the door. Pushing at a special angle gives a smaller turning effect.
(a) Moment of force is often reduced by reducing the space between force and thus the turning point.

Note:The moment of force is also a vector quantity. Moment of force is often increased by increasing the space between force and thus the turning point. To maintain the static balance of a body, the sum of external forces and the sum of external moments of force acting on that body should be zero.