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 27°c to 850 kpa 2-3 isothermal expansion until v 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) the back work ratio