A tiny sphere of mass 7.90 µg and charge ?2.80 nC is initially at a distance of 1.74 µm from a fixed charge of +8.93 nC. (a) If the 7.90-µg sphere is released from rest, find its kinetic energy when it is 0.500 µm from the fixed charge. (b) If the 7.90-µg sphere is released from rest, find its speed when it is 0.500 µm from the fixed charge.