Moment is mathematically and physically identical to torque. The term moment is typically used in applications where a [[Force|force]] applied at a [[Distance|distance]] to a pivot point will cause rotation in a structure. The term torque is typically used for applications on an axle, such as a gear shaft. Moment is defined by taking the [[Vector Operations|cross product]] of a force and the distance between the force and the pivot point of interest, $r$. $\vec{M}=\vec{r}\times\vec{F}$ ![[Moment.png|center|300]] Since moment is defined by cross product it is a [[Vector|vector]]. The direction of rotation is defined by the [[Right Hand Rule|right-hand rule]]. A couple is a special type of moment. Couples occur when two equal and opposite parallel forces applied to an object are separated by a distance. In the case of a couple a moment does not require a reference point as it will be equal at all points. For this reason couples are deemed free vectors, they can be moved anywhere on an object and not change the result of the analysis.