$A$ fully loaded Boeing aircraft has a mass of $3.3 \times 10^{5} \; kg$. Its total wing area is $500 \; m^{2}$. It is in level flight with a speed of $960 \; km/h$.
$(a)$ Estimate the pressure difference between the lower and upper surfaces of the wings.
$(b)$ Estimate the fractional increase in the speed of the air on the upper surface of the wing relative to the lower surface. [The density of air is $\rho = 1.2 \; kg/m^{3}$]

(N/A) The weight of the Boeing aircraft is balanced by the upward force due to the pressure difference.
$\Delta P \times A = m \times g$
$\Delta P = \frac{3.3 \times 10^{5} \; kg \times 9.8 \; m/s^{2}}{500 \; m^{2}} = 6.468 \times 10^{3} \; N/m^{2} \approx 6.5 \times 10^{3} \; N/m^{2}$.
$(b)$ Ignoring the small height difference,Bernoulli's principle gives the pressure difference as:
$\Delta P = \frac{\rho}{2} (v_{2}^{2} - v_{1}^{2}) = \frac{\rho}{2} (v_{2} - v_{1})(v_{2} + v_{1})$
Given $v_{av} = \frac{v_{1} + v_{2}}{2} = 960 \; km/h = 266.7 \; m/s$.
$\frac{v_{2} - v_{1}}{v_{av}} = \frac{\Delta P}{\rho \cdot v_{av}^{2}} = \frac{6.5 \times 10^{3}}{1.2 \times (266.7)^{2}} \approx 0.076 \approx 0.08$.
The speed above the wing needs to be approximately $8\%$ higher than that below.