A 50-ft3 uninsulated tank contains air at 150 lbf/in 2, 1000 R. The tank is now discharged through a small convergent nozzle to the atmosphere at 14.7 lbf/in 2 while heat transfer from some source keeps the air temperature in the tank at 1000 R. The nozzle has an exit area of 2 104 ft2. a. Find the initial mass flow rate out of the tank. b. Find the mass flow rate when half the mass has been discharged. c. Find the mass of air in the tank and the mass flow rate out of the tank when the nozzle flow changes to become subsonic.