A small ball of mass 1 kg and charge `(2)/(3)mu` C is placed at the centre of a uniformly charged sphere of radius 1 m and charge `(1)/(3)mC`. A narrow smooth horizontal groove is made in the sphere from centre to suface as shown in figure. The sphere is made to rotate about its vertical diameter at a constant rate of `(1)/(2pi)` revolutions per second. Find the speed w.r.z ground (in m/s) with which the ball slides out from the groove. Neglect any magnetic force acting on ball.

Answer

B