Helium at 810 R, 45 Ibf/in^2, and a velovity of 10 ft/s enters an insulated nozzle operating at steady state and exits at 690 R, 25 Ibf/in^2. modeling helium as an ideal gas with k = 1.67 and R = 0.496 Btu/Ibm.R and Cp = 1.236 Btu/Lbm.R determine:
A)the velocity at the nozzle exit in ft/s
B) the isentropic nozzle efficiency
C)the rate of entropy production (deltaS) within the nozzle in Btu/lbm.R