A $0\mathrm{.}25$ pgpg dust particle with $50$ excess electrons is sitting at rest on top of a $5\mathrm{.}0-$cmcm$-$diameter metal sphere. Closing a switch charges the sphere almost instantaneously.

Part A

To what potential must the sphere be charged to launch the dust particle to a height of $6\mathrm{.}0$ mm$?$ Ignore air resistance.