Contour Integral/Examples/Work Done

Example of Line Integral
Let $\mathbf F$ be a force acting as a point-function giving rise to a vector field $\mathbf V$.

Let $OA$ be a curve in $\mathbf V$ along which a particle $P$ is moved by $\mathbf F$.

Let $\d \mathbf l$ be a small element of length of $OA$ at $P$.

Then the work done by $\mathbf F$ moving $P$ from $O$ to $A$ is given by the line integral:
 * $\ds \int_O^A \mathbf F \cdot \d \mathbf l$