Question

what is the change in internal energy, \\( \delta u \\), in joules, for a system that absorbs 575 j of heat and does 415 j of work on its surroundings?

• 160 j

+ 575 j

• 415 j

+ 990 j
+ 160 j

Explanation:

Step1: Recall the first law of thermodynamics

The first law of thermodynamics is given by the formula $\Delta U=Q + W$, where $Q$ is the heat absorbed by the system and $W$ is the work done on the system.

Step2: Determine the sign of $Q$ and $W$

Since the system absorbs heat, $Q = + 575\space J$. The system does work on the surroundings, so $W=-415\space J$ (work done by the system is negative).

Step3: Substitute values into the formula

Substitute $Q = 575\space J$ and $W=-415\space J$ into $\Delta U=Q + W$. Then $\Delta U=575+(- 415)$.

Step4: Calculate $\Delta U$

$\Delta U=575 - 415=160\space J$

Answer:

+ 160 J