Particle Q$1=3\mathrm{.}2$ mu C has a mass of $6\mathrm{.}5$ mu g$,$ and particle Q$2=3\mathrm{.}5$ mu C has a mass of $7\mathrm{.}6$ mu g$.$  The two$-$charges are initially separated by a distance of $2\mathrm{.}4$ cm$.$ With charge Q$1$ held in place, charge Q$2$ is released from rest. What is the speed, in meters per second, of charge Q$2$ when it is $6\mathrm{.}7$ cm from charge Q$1?$