Consider a venturi with a throat-to-inlet area ratio of 0.8, mounted on the side of an airplane fuselage. The airplane is in flight at standard sea level. If the static pressure at the throat is 2100 lb/ft^2, calculate the velocity of the airplane.

Throat to inlet air ratio =$0.8$

Static pressure at the throat = $2100\;lb/ft^{2}$

We need to calculate here the velocity of airplane. $$V_{1}=\sqrt{\frac{2\left ( P_{1} -P_{2}\right )}{\rho \left [ \left ( \frac{A_{1}}{A_{2}} \right )^{2}-1 \right ]}}$$

Here $P_{1}=2116\;lb/ft^{2},P_{2}=2100\;lb/ft^{2},A_{2}/A_{1}=0.8$

Therefore $$V_{1}=\sqrt{\frac{2\left ( 2116-2100 \right )}{\left ( 0.002377\right )\left [ \left ( \frac{1}{0.8} \right )^{2} -1\right ] }} \\=154.7\;ft/sec$$

The velocity of the airplane is $154.7\;ft/sec$.