Acylinder of gas is compressed by a piston from an initial volume of 125 liters to a final volume of 90 liters. the compression occurs at constant pressure, and the work done on the gas by the piston is 104 joules. what is the gas pressure during the compression? (1 liter = 10-3 meters3)

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.