Physics Question... thank you! :)?

Redstone Arsenal has asked your team of students about the feasibility of a new projectile launcher that will save rocket fuel. Their idea is basically an electric slingshot that consists of 4 electrodes arranged in a horizontal square with sides of length 2d at a height h above the ground. The projectile is then placed on the ground aligned with the center of the square. A power supply will provide each of the four electrodes with a charge of +Q/4 and the projectile with a charge -Q. When the projectile is released from rest, it moves up and pes through the center of the square. To test this idea you decide to use energy consideration to calculate how large Q will have to get a 100kg projectile to achieve the Earth’s escape velocity of 11.2 km/sec when it pes through the square’s center. ume that the projectile starts from 100 meters below the horizontal square of electrode and that the sides of the square are each 10 meters in length in the calculation of Q. Furthermore, the plan is to ground the electrodes as the projectile pes through the square’s center, thereby giving the electrodes a zero electric charge. Why would you plan to ground the electrodes? Estimate the amount of current which will necessary to neutralize the four electrodes as the 0.50-m long projectile pé through the center of the array.