Chapter 6 Question 9 Answer:

(2) ws > w > 0 > wf

For an adiabatic turbine ws = -cp(DT), w = -cv(DT), and wf = R(DT), and DT < 0. For air, cp > cv > R. Therefore ws > w > 0 > wf. This illustrates an important point regarding shaft work and flow work. For a steady flow device, what you would like to design to is the work that comes out of the shaft. If you calculate the total work (w), you will get a different answer.

Class Response (2003):

Class Response (2002):