A converging$-$diverging nozzle with a $4$:$1$ exit$-$area ratio and p$0=520$ kPa operates in an underexpanded condition as in the image. The receiver pressure is pa $=10$ kPa, which is less than the exit pressure, so that expansion waves form outside the exit. For the given conditions, what will the Mach number Ma$2$ and the angle $\backslash$phi of the edge of the jet be$?$ Assume k $=1\mathrm{.}4$ as usual.