Ten kilograms per second of air is flowing in an adiabatic system. At one section, the pressure is \(2.0 \times 10^{5} \mathrm{~N} / \mathrm{m}^{2}\), the temperature is \(650^{\circ} \mathrm{C}\), and the area is \(50 \mathrm{~cm}^{2}\). At a downstream section \(M_{2}=1.2\).
(a) Sketch the general shape of the system.
(b) Find \(A_{2}\) if the flow is frictionless.
(c) Find \(A_{2}\) if there is an entropy change between these two sections of \(42 \mathrm{~J} / \mathrm{kg}-\mathrm{K}\).