Steam at 6.0 MPa and 700 K enters a converging nozzle with a negligible velocity. The nozzle throat area is 8 cm2. Approximating the flow as isentropic, plot the exit pressure, the exit velocity, and the mass flow rate through the nozzle versus the back pressure Pb for 6.0 $ Pb $ 3.0 MPa. Treat the steam as an ideal gas with k = 1.3, cp = 1.872 kJ/kg·K, and R = 0.462 kJ/kg·K.