An external heat source supplies heat to a system at a rate of 187 W as the system does work at a rate of 131 W.At what rate is the internal (thermal)energy of the system changing?
A)-56 W
B)320 W
C)56 W
D)190 W
E)-320 W

Question

Quizplus · Accepted Answer

The rate of change in internal energy of the system can be found using the first law of thermodynamics, which in this context is given by the formula: $\Delta U = Q - W$, where $\Delta U$ is the change in internal energy, $Q$ is the heat added to the system, and $W$ is the work done by the system. Plugging in the given values, we get $\Delta U = 187\,W - 131\,W = 56\,W$. This means the internal energy of the system is increasing at a rate of 56 W.

An External Heat Source Supplies Heat to a System at a Rate