Air flows adiabatically in a 3-cm-diameter duct, with f = 0.018. At the entrance, T1 = 323 K, p1 = 200 kPa, and V1 = 72 m/s. (a) What is the mass flow? (b) For what tube length will the flow choke? (c) If the tube length is increased to 112 m, with the same inlet pressure and temperature, what will be the new mass flow