A system performs 800 J of work while taking in 500 J of heat. What is the change in internal energy of the system?
A) not possible.
B) 300 J
C) −300 J
D) 1,300 J
E) −1,300 J

Question

Quizplus · Accepted Answer

According to the first law of thermodynamics, the change in internal energy (ΔU) is given by ΔU = Q - W, where Q is the heat added to the system and W is the work done by the system. Here, Q = 500 J and W = 800 J, so ΔU = 500 J - 800 J = -300 J.

A System Performs 800 J of Work While Taking in 500