Question

NASA has asked your team of rocket scientists about thefeasibility of a new projectile launcher that will save rocketfuel. NASA's idea is basically an electric slingshot that consistsof 4 electrodes arranged in a horizontal square with sides oflength d at a height h above the ground. The projectile is thenplaced on the ground aligned with the center of the square. A powersupply will provide each of the four electrodes with a charge of+Q/4 and the projectile with a charge -Q. When the projectile isreleased from rest, it moves up and passes through the center ofthe square. At the instant it reaches the square's center, thepower supply is turned off and the electrodes are grounded, givingthem a zero electric charge. To test this idea, you decide to useenergy considerations to calculate how big Q will have to be to geta 100 kg projectile to achieve a speed of 343 m/s. Assume that theprojectile starts from 15 meters below the square of electrodes andthat the sides of the square are each 5 meters. Estimate the amountof current which will be necessary to neutralize the fourelectrodes as the projectile passes through.