A tiny sphere of mass 7.80 mg and charge -2.80 nC is initially at a distance of 1.74 μm from a fixed charge of +8.05 nC.
(a) If the 7.80-mg sphere is released from rest, find its kinetic energy when it is 0.500 μm from the fixed charge.
(b) If the 7.80-mg sphere is released from rest, find its speed when it is 0.500 μm from the fixed charge.