A rotational force, also known as a torque, depends upon the force and where that force is applied;
The lever arm is the perpendicular distance from the force to the axis of rotation.
A "lever arm" is also known as a "moment arm".
Consider the torque exerted on this wrench by a force applied in different directions or in different places.
Consider the rotational force -- or the torque -- acting on a door when you try to open it by exerting a force in various places or in various directions.
(C) 2003, Doug Davis; all rights reserved