Air enters the duct of an air-conditioning system at 15 psia and 50 F at a volume flow rate of 450 ft3/min. The diameter of the duct is 10 inches and heat is transferred to the air in the duct from the surroundings at a rate of 2 Btu/s. Determine (a) the velocity of the air at the duct inlet and (b) the temperature of the air at the exit.