A-3.25 consider a naca 2415 airfoil section in a low-speed wind tunnel. assume re 9 x 106 a) what is the zero-lift angle of attack? b) does this airfoil have negative or positive camber? c) what is the stalling angle of attack? d) what is the maximum value of ci? e) what is the lift-curve slope?

Objects a and b are visible in the night sky. six months later they are still visible, but object b shows less parallax than object a. which object is closer? a. a b. b c. you would need to wait another six months in order to figure this out. d. you would need to know the objects' angular diameters in order to figure this out.