A cell membrane separates three species of ions (Na+, Cl-, K+). The Nernst potentials are: VNa = 50 mV, Vcl = -60 mV, VK = -100 mV. The membrane potential is held to be constant at Vm = -70 mV. Given that gNa = 1 pS, gcl = 2 pS, and gK = 4 pS:(a) Calculate the electrical current carried by each of the ion species.(b) Indicate the direction that each of the species is transported across the membrane.

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.