A fluid in an insulated, flexible bottle is heated by a high resistance wire and expands. If $9.0 \mathrm {~kJ}$ of heat is applied to the system and it does $5.0 \mathrm {~kJ}$ of work, how much does the internal (thermal)energy of the fluid change?
A)4.0 kJ
B)14 kJ
C)-4.0 kJ
D)45 kJ

Question

Quizplus · Accepted Answer

The change in internal energy is given by the first law of thermodynamics: $\Delta U = Q - W$. Here, $Q = 9.0 \mathrm{~kJ}$ and $W = 5.0 \mathrm{~kJ}$, so $\Delta U = 9.0 \mathrm{~kJ} - 5.0 \mathrm{~kJ} = 4.0 \mathrm{~kJ}$.

A Fluid in an Insulated, Flexible Bottle Is Heated by a High