A small sphere with mass 5.00 10 -7 kg and charge +7.00 C is released from

A small sphere with mass 5.00 × 10^-7 kg and charge +7.00 µC is released from rest a distance of 0.400 m above a large horizontal insulating sheet of charge that has uniform surface charge density σ = +8.00 pC/m². Using energy methods, calculate the speed of the sphere when it is 0.100 m above the sheet.