3.19. An ideal gas initially at 600 K and 10 bar undergoes a four-step mechanically reversible cycle in a closed system. In step 12, pressure decreases isothermally to 3 bar;

instep 23, pressure decreases at constant volume to 2 bar, in step 34, volume decreases at constant pressure; and in step 41 . the gas returns adiabatically to its initial state.Take Cp = (7/2)R and Cv = (5/2)R. (a) Sketch the cycle on a PV diagram. (b) Determine (where unknown) both T and P for states 1. 2. 3. and 4. (c) Calculate Q. W, AU, and AH for each step of the cycle.

Fig: 1

Fig: 2

Fig: 3

Fig: 4