The force exerted by an electric charge at the origin on a charged particle at a point $(x, y, z)$ with position vector
$\mathbf{r}=\langle x, y, z\rangle$ is
$\mathbf{F}(r)=\frac{K \mathbf{r}}{|\mathbf{r}|^{3}}$
where $K$ is a constant. (See this example.) Find the work done as the particle moves along a straight line from $(5,0,0)$ to $(5,3,5)$.