Definition:Torque

Definition
Torque is a measure of strength of a force to effect rotation of a body.

Let $\mathbf F$ be a force acting at a point on a body $B$.

Let $B$ rotate around a point $O$ as a consequence of the action of $\mathbf F$.

Let $\mathbf r$ be the position vector of $P$ $O$, that is:
 * $\mathbf r = \vec {OP}$

The torque about $O$ is defined as the cross product of the vector $\mathbf r$ and $\mathbf F$:


 * $\bstau = \mathbf r \times \mathbf F$

Torque is a vector quantity.