What is the value of increase in internal energy when system does $8 \mathrm{~J}$ of work on surrounding by…
What is the value of increase in internal energy when system does $8 \mathrm{~J}$ of work on surrounding by supplying $40 \mathrm{~J}$ of heat to it?
$23 \mathrm{~J}$
$32 \mathrm{~J}$
$40 \mathrm{~J}$
$48 \mathrm{~J}$
Solution
Heat $(Q)=+40 \mathrm{~J}$
Work $(W)=-8 \mathrm{~J}$
According to first law of thermodynamics,
$\begin{aligned}
& \Delta \mathrm{U}=\mathrm{Q}+\mathrm{W} \\
& \Delta \mathrm{U}=(+40-8) \mathrm{J} \quad \therefore \quad \Delta \mathrm{U}=+32 \mathrm{~J}
\end{aligned}$