A system does $394 \mathrm{~J}$ of work on surrounding by absorbing $701 \mathrm{~J}$ heat. What is the…
A system does $394 \mathrm{~J}$ of work on surrounding by absorbing $701 \mathrm{~J}$ heat. What is the change in internal energy of the system?
$547 \mathrm{~J}$
$1095 \mathrm{~J}$
$307 \mathrm{~J}$
$394 \mathrm{~J}$
Solution
$\mathrm{W}=-394 \mathrm{~J} \quad$ work done by system $(-)$ ve
$\mathrm{q}=+701 \mathrm{~J} \quad$ Heat absorbed by system $(+)$ ve From First law of thermodynamics.
$\begin{aligned}
& \Delta \mathrm{U}=\mathrm{q}+\mathrm{W} \\
& =701-394 \\
& =307 \mathrm{~J}
\end{aligned}$