The work done in moving a $-5\muC$ charge in an electric field $ \overrightarrow{E} = (8r sin \theta \hat{r}+ + 4r cos \theta \hat{\theta} ) V/m$, from a point $A(r, \theta) = (10,\frac{\pi}{6})$ to a point $B(r,\theta) (10.\frac{\pi}{6})$ is _____ $mj$.