Two small spheres are attached to the ends of a long, light, non-conducting rod 40 mm from each other . A third, “middle” sphere can slide along the rod without friction. Each of the three spheres are non-conducting, have identical masses m, and a positive charge q distributed uniformly on the sphere’s surface. The whole system is placed on a horizontal, frictionless, non-conducting surface. Initially, all three spheres are at rest with the middle sphere located a distance 3d from one end of the rod and a distance d from the other end. Find the maximum speed (v) of the middle sphere after the system is released