A very small object with mass 8.20 × 10^-9 kg and positive charge 6.50 × 10^-9 C is projected directly toward a very large insulating sheet of positive charge that has uniform surface charge density 5.90 × 10^-8 C/m². The object is initially 0.400 m from the sheet. What initial speed must the object have in order for its closest distance of approach to the sheet to be 0.100 m?