Apoint source of light is submerged 2.9 m below the surface of a lake and emits rays in all directions. on the surface of the lake, directly above the source, the area illuminated is a circle. what is the maximum radius that this circle could have? take the refraction index of water to be 1.333.

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.