Three processes compose a thermodynamic cycle shown in the accompanying pV diagram of an ideal gas.
Process 1→2 takes place at constant temperature (300 K). During this process 60 J of heat enters the system.
Process 2→3 takes place at constant volume. During this process 40 J of heat leaves the system.
Process 3→1 is adiabatic. T3 is 275 K.
What is the change in internal energy of the system during process 3→1?
(A) –40 J
(B) –20 J
(C) 0 J
(D) +20 J
(E) +40 J
