A long thick solid conductor has a cylindrical cavity of radius 1 m parallel to its axis at a distance of 2m from centre of cylinder. Cylinder have uniform  surface current density  $J=\frac{{10}^6}{\pi }A/m^2\widehat{k}$  A charged particle of mass  0.1 kg and charge  $\pi$ coulomb is projected with velocity v at an angle of 60º as shown in figure.  For what maximum v, particle is able to  strike point B?