In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower s

Question

In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wing are $70	ext{ m/s}$ and $63	ext{ m/s}$ respectively. What is the aerodynamic lift on the wing if its area is $2.5	ext{ m}^2$? (Density of air = $1.3	ext{ kg/m}^3$)

Professor PC Thomas Classes · Answer

Lift force $F = \Delta P 	imes A$. By Bernoulli's principle, $\Delta P = \frac{1}{2} ho (v_{upper}^2 - v_{lower}^2) = \frac{1}{2} 	imes 1.3 	imes (70^2 - 63^2) = 0.65 	imes 931 = 605.15	ext{ Pa}$. Therefore, $F = 605.15 	imes 2.5 \approx 1512.8	ext{ N} \approx 1.5 	imes 10^3	ext{ N}$.