physics
posted by Jaime .
Air streams horizontally past a small airplane's wings such that the speed is 70.0m/s over the top surface and 60.0m/s past the bottom surface. If the plane has a wing area of 16.2m^2 on the top and on the bottom, what is the net vertical force that the air exerts on the airplane?

http://hyperphysics.phyastr.gsu.edu/Hbase/pber.html
As a first approximation assume the density of the air is the same on the bottom side as the top.
Pbottom+d*1/2 *Vbottom^2=Pressuretop + d*1/2*Vtop^2
or pressuretoppressurebottom=d*1/2(Vtop^2Vbottom^2)
So, after you calculate that pressure difference, multipy it by the wing area, and you have the lift force.