Question

A system generates $50J$ of electrical energy, has $150J$ of pressure-volume work done on it by the surroundings while releasing $300J$ of heat energy. What is the change in the internal energy of the system?

• A. $-500$
• B. $-100$
• C. $-300$
• D. $-200$

Answer 1

Answer: (D)

$-200$

$dU=dq+dw$;

where $dw={dw}_{pv}+{dw}_{non-pv}$,

so,

$dU=-300+150-50=-200J$