the work done by an external force to move a $-8\mathrm{.}0$ uC charge, Q$,$ from a to b is $25\mathrm{.}0$x$10^-4$ J$.$ If the charge started from rest and has $5\mathrm{.}2$x$10^-4$J of kinetic energy when it reached point b$,$ what is the potential difference, V$,$ between points a and b$?$