3. Natural gas expands isentropically through a duct from 25 psia and 160 F to 15.1 psia and 8500 ft/s. Compute the exit temperature, Mach number, stagnation temperature, and stagnation pressure. Also compute the inlet velocity and determine whether the flow is sonic, supersonic or subsonic at inlet and outlet conditions. For natural gas R = 3100 lbf.ft/SlugR; k = 1.31. Make sure to use geconversion when necessary. Hint: Watch "Chapter 11-CO2 Isentropic flow.mp4" or in class example