A small ball of mass 1 kg and charge  q=23 μC is placed at the centre of a uniformly charged sphere of radius 1 m and charge  Q=13 mC. A narrow smooth horizontal groove is made in the sphere from centre to surface as shown in figure. The sphere is made to rotate about its vertical diameter at a constant rate of  12π revolutions per second. Find the speed w.r.t. ground (in m/s) with which the ball slides out from the groove. Neglect any magnetic force acting on ball.  Take,  14πε0=9×109  Nm2C2