If there is a hole in a water tank, water will shot out due to water pressure.
You can drag the hole up and down to change its position.

Click show baseline checkbox, drag the hole up and down , and find out when the horizontal displacement is maximum?

$\rho g h =\frac{1}{2} \rho v_x^2$ , so $vx=\sqrt{2\,g\, h}$