Car A is traveling west at 70 mi/hr and car B is traveling north at 80 mi/hr. Both cars are headed for the intersection of the two roads. At what rate are the cars approaching each other when car A is 0.3 mi and carB 0.4 mi from the intersection?

The ratio of lift to drag l/d for a wing or airfoil is an important aerodynamic parameter, indeed, it is a direct measure of the aerodynamic efficiency of the wing. if a wing is pitched through a range of angle of attack, l/d first increases, then goes through a maximum, and then decreases. consider an infinite wing with an naca 2412 airfoil. estimate the maximum value of l/d. assume that the reynolds number is 9x10^6.