'Example (5-4): An airstream at Mach 2.0 with pressure of 100 kPa and temperature of 270 K enter diverging channel, with ratio of exit area to inlet area of 3.0. Determine the back pressure necessary t0 produce a normal shock in the channel at an area equal to twice the inlet area Assume one-dimensional steady flow, with the air behaving as perfect gas with constant specific heats; assume isentropic flow except for the normal shock_'