1. Air at 25-C and 240 kPa ?ows in a 10-cm-diameter pipe at 40 m=s. What are the ?ow rate and the mass ?ux in the pipe? (Recall that pressures are always gauge pressures unless stated otherwise.)
2. Air ?ows in a 20-cm-diameter duct at 120-C and 120 kPa with a mass ?ux of 5 kg=s. The circular duct converts to a 20-cm square duct in which the temperature and pressure are 140-C and 140 kPa, respectively. Determine the velocities in both sections of the duct.