$${\begin{align*} v &= \frac{m + M}{m} \sqrt{2gh} \\&= \left( \frac{0,0095\, \mathrm{kg} + 5,5\, \mathrm{kg}}{0,0095\, \mathrm{kg}}\right) \sqrt{(2)(9,8\, \mathrm{m/s^2})(0,063\, \mathrm{m})} \\&= \underline{\underline{630\, \mathrm{m/s}}}\end{align*}}$$