Answer
20.9 m/s
Work Step by Step
Please see the attached image first.
Let's apply Bernoulli's equation to the system to find the speed of the water.
$P+\frac{1}{2}\rho v^{2}+\rho gh=constant$
$1.01\times10^{5}Pa+(1000\space kg/m^{3})(9.8\space m/s^{2})(12\space m)+0=0+\frac{1}{2}(1000\space kg/m^{3}) v_{2}^{2}+0$
$v_{2}=20.9\space m/s$
