In a thermodynamic process, the internal energy of a system in a container with adiabatic walls decreases by 800 J. Which statement is correct?

Question

Quizplus · Accepted Answer

Since the walls are adiabatic, there is no heat transfer. Therefore, the decrease in internal energy must be due to work done by the system on its surroundings, according to the first law of thermodynamics (ΔU = Q - W, where Q is heat and W is work). Since the internal energy decreased, this means work was done by the system on its surroundings, so the answer is (C) "The system performed 800 J of work on its surroundings."

In a Thermodynamic Process, the Internal Energy of a System