Steam enters an adiabatic turbine at 6 MPa, 600oC, and 80 m/s and leaves at 50 kPa, 100oC, and 140 m/s. If the power output of the turbine is 5 MW, determine: (a) the total rate of change in exergy of the steam passing through the turbine, and (b) the exergetic efficiency of the turbine. Assume the surroundings to be at 25oC and 100 kPa.