Essential University Physics: Volume 1 (3rd Edition)

Using conservation of energy, we find: $\frac{1}{2}(\frac{mv}{m+M})^2 = gh \\ (\frac{mv}{m+M})^2 = 2gh \\ (\frac{mv}{m+M}) = \sqrt{2gh} \\ v = (\frac{m+M}{m})\sqrt{2gh}$