The measure of rotation about a reference object when a force is applied. When a reference point is used, the moment is the cross product of the amount of force and the perpendicular distance between the point and the line of force. When a reference line is used, the moment is the cross product of amount of force and the shortest distance between the line and the point where the force is applied. When a reference plane is used, the moment is the cross product of the amount of force and the perpendicular distance from the plane to the point where the force is applied.