An air-standard cycle is executed within a closed piston–cylinder system, and it consists of the following three processes: 1–2 v = constant heat addition from 100 kpa and 34°c to 850 kpa 2–3 isothermal expansion until v3 = 8.5v2 3–1 p = constant heat rejection to the initial state assume air has constant properties with cv = 0.718 kj/kg·k, cp = 1.005 kj/kg·k, r = 0.287 kj/kg·k, and k = 1.4. determine the ratio of the compression work to the expansion work (the back work ratio).