Torque vs Couple
Moment, torque and couple are concepts often encountered by students studying physics and these are also terms that are often confused by them. There are similarities between a torque and a couple but there are striking differences also that will be explained in this article.
Torque is a special kind of force that has the capacity to rotate an object about an axis. While a force is described as a push or a pull, it is better to think of torques as a twist. Daily life examples of a torque are when you use your hands to turn the steering of your car or when you try to unscrew a nut using a wrench. Simply speaking, a torque is a turning force. You apply force on the wrench which opens the screw. However, students get confused as this fore is called a torque when they study physics at school but the same force is referred to as moment while studying it in mechanical engineering.
In a special case when applied force vectors add to zero, then the force is called a couple and their moment is called a torque. Thus the rotational force that produces no moment is called a couple. Couple is also referred to as a pure moment. The most basic kind of couple takes place when two equal but opposite forces act on a body whose lines of forces do not coincide. The SI unit of a couple is Newton-meter.
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Torque vs Couple • The turning effect produced by a force on a body is called torque. It is calculated as force multiplied by perpendicular distance. • A couple is a special case when there are two equal but opposite forces acting on a body that rotate it.
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