When $\mathrm{x} \mathrm{kJ}$ heat is provided to a system, work equivalent to $\mathrm{y} \mathrm{J}$ is…
When $\mathrm{x} \mathrm{kJ}$ heat is provided to a system, work equivalent to $\mathrm{y} \mathrm{J}$ is done on it. What is internal energy change during this operation?
$(1000 x+y) J$
$1000(x+y) J$
$(x+1000 y) J$
$x+y ~ J$
Solution
$\begin{aligned}
& \mathrm{Q}=+\mathrm{xkJ}=1000 \mathrm{x} \mathrm{J} \\
& \mathrm{W}=+\mathrm{y} \mathrm{J}
\end{aligned}$
From I law of Thermodynamics
$\begin{aligned}
& \Delta U=Q+W \\
& =(1000 x+y) J
\end{aligned}$