Energy Example
Since Volts are asked for, and voltage is connected to potential energy, this suggests we use Conservation of Energy.
We can use the Conservation of Energy including the formulas for kinetic energy and potential energy:
KEi + PEi = KEf + PEf + Elost , where
KE = (1/2)mv2 and PE = qV:
(1/2)mpvi2 + qpVi = (1/2)mpvf2 + qpVf + Elost
Since vi=0 and Elost=0, and bringing qpVf to the left side, we have: qp(Vi-Vf) = (1/2)mpvf .