Question: Air is expanded from a large reservoir, in which the pressure and temperature are 250 kPa and 30°C, respectively, through a convergent nozzle that gives an exit Mach number of 0.3. The air from the nozzle flows down a pipe having a diameter of 5 cm. The Mach number at the end of this pipe is 0.95. Find the length of the pipe and the pressure at the end of the pipe. If the actual pipe length was only 0.75 of this length, find the Mach number and the pressure that would exist at the end of the pipe. The flow in the nozzle can be assumed to be isentropic and the friction factor in the pipe can be assumed to be 0.005.