Answer
${\frac{V}{\sqrt{g l}}}\,=1.25$
Work Step by Step
In British Uints
$\frac{V}{\sqrt{g l}}=\frac{10 \frac{f t}{s}}{\sqrt{\left(32.2 \frac{f t}{s^2}\right)(2 f t)}}=1.25$
In SI units
$\begin{aligned} & V=\left(10 \frac{\mathrm{ft}}{\mathrm{s}}\right)\left(0.3048 \frac{\mathrm{m}}{\mathrm{ft}}\right)=3.05 \frac{\mathrm{m}}{\mathrm{s}} \\ & g=9.81 \frac{\mathrm{m}}{\mathrm{s}^2} \\ & l=(2 \mathrm{ft})\left(0.3048 \frac{\mathrm{m}}{\mathrm{ft}}\right)=0.610 \mathrm{~m}\end{aligned}$
$\frac{V}{\sqrt{g l}}=\frac{3.05 \frac{\mathrm{m}}{\mathrm{s}}}{\sqrt{\left(9.81 \frac{\mathrm{m}}{\mathrm{s}^2}\right)(0.610 \mathrm{~m})}}=1.25$
so The value of dimensionless parameter doesn't depend on the unit system
