Electricity with conservation of energy involved.

[-Entropy-]

A tiny sphere of mass 7.70 µg and charge −2.80 nC is initially at a distance of 1.74 µm from a fixed charge of +9.25 nC.
(a) If the 7.70-µg sphere is released from rest, find its kinetic energy when it is 0.500 µm from the fixed charge.

(b) If the 7.70-µg sphere is released from rest, find its speed when it is 0.500 µm from the fixed charge.
m/s

 

[haruspex]

As per the rules, please post any equations you deem relevant and your attempt at solution (or a clear statement of what hinders you from getting started).