If a closed system undergoes a process during which it receives energy by heat transfer and work is done on the system, the total energy of the system must increase.

A closed system undergoes a thermodynamic cycle with three steps: process 1-2 (from state 1 to state 2), process 2-3 (from state 2 to state 3), process 3-1 (from state 3 to state 1). During process 1-2, the system received energy by heat transfer of 5J and did work of 10J. During process 2-3, the system was transferred energy from its surrounding by heat transfer of 25J and work was done on the system of 20J. During process 3-1, the system discharged 40J to its surrounding by heat transfer. What is the net work in this cycle?

There is a piston-cylinder system that undergoes a process. The total work done by the system, W, is 50 kJ, and thechange in the specific internal energy of the system, Δu, is −7 kJ/kg. We also know the total mass of the system, m, is 10kg. During the process, both the change of kinetic energy and the change of potential energy are negligible. Pleasedetermine 1) the total energy change, ΔE, in kJ; 2) the total heat transfer, Q, in kJ; and 3) judge the direction of energyflow for the heat transfer: into the system or out of the system.

The net change in volume (a property) during a cycle is always zero.