In free space, a particle A of charge 1 $\mu$C is held fixed at a point P. Another particle B of the same charge and mass 4 $\mu$g is kept at a distance of 1 mm from P. If B is released, then its velocity at a distance of 9 mm from P is : $\left[Take\frac{1}{4\pi {\in }_0}=9\times {10}^{9}N{m}^2{C}^{-2}\right]$