A system does 80 J of work on its surroundings and releases 20 J of heat into its surroundings. What is the change of energy of the system?[Use U=Q-W a. -60 j
b. 60 j
c. -100 j
d. 100 j

Agas contained within a piston-cylinder assembly undergoes three processes in series: process 12: compression with pv= constant from 1 bar and 1 liter to 4 bar. process 23: constant pressure expansion to 1 liter. process 31: constant volume calculate the pressure and volume at each state, and sketch the processes on a p-vdiagram labeled with pressure and volume values at each numbered stat