Acircular fin (k=100 w/m-k) of length l 25 cm and diameter d=50 mm extends between the upper and lower walls of an air duct, which are both held at a constant temperature of t-20c, hot air flows over the sides of the fin with a freestream temperature t 40'c and a convection coefficient h 40 w/m'-k. (a) starting with an appropriate differential control volume, derive an equation for the temperature variation t) through the fin. clearly indicate your control volume and the various terms in the energy balance. (b) sketch the temperature variation t(x) through the fin, and indicate where the conduction heat flux through the fin is maximum. (c) determine the total amount of heat dissipated by the fin into the airflow