A system has an increase in internal energy of 60 J while 90 J was removed from the system by heat. How much work was involved during this process and was it done on the system or done on its environment?
On a PV diagram, 2 curves are plotted, both starting at the same point (P1, V1) and both ending at the same increased volume (V2). One curve is for an isothermal process; the other is for an adiabatic process. Except for the common starting point, which curve is the upper one?