Force Couples: A force couple consists of two parallel forces of equal magnitude and opposite direction separated by a finite distance. The net result is a couple moment of magnitude M = Fd. It is important to realize that a couple moment is a free vector meaning that it can be shown at any point on the body as long as its magnitude and direction are not altered.
 |
|
|
Force couples appear in many problems, and they represent a practical way for applying moments on a body. For example, when one uses a cross wrench to loosen or tighten the lug nuts on a wheel of a car, the applied forces at the opposite ends of the cross wrench form a couple. Also by having both hands on the steering wheel of a car, we can apply a couple to turn the wheel. |
 |