Problem: How fast must air move over the upper surface at a cruising speed of 240 m/s and at an altitude where air density is one-fourth that at sea level? (Note that this is not all of the aircraft's lift-some comes from the body of the plane, some from engine thrust, and so on. Furthermore, Bernoulli's principle gives an approximate answer because flow over the wing creates turbulence.)
I don't know how to get that answer for the above problem. Please help! Thanks.