Question 11 Mark
A system goes from P to Q by two different paths in the P-V diagram as shown in Fig. Heat given to the system in path 1 is 1000J. The work done by the system along path 1 is more than path 2 by 100J. What is the heat exchanged by the system in path 2?
Answer
View full question & answer→For path (1) $\mathrm{Q}_1=+1000 \mathrm{~J} \mathrm{~W} . \mathrm{D}=\mathrm{W}_1, \mathrm{~W}_2=100 \mathrm{~W}_1=\mathrm{WD}$ through path $1 \mathrm{~W}_2=\mathrm{WD}$ through path $2 \therefore \mathrm{~W}_2=\mathrm{W}_1-100 \mathrm{As}$ change in internal energy by path 1 and 2 are same
$\Delta \mathrm{U}=\mathrm{Q}_1-\mathrm{W}_1=\mathrm{Q}_2-\mathrm{W}_2$
$1000-\mathrm{W}_1=\mathrm{Q}_2-\left(\mathrm{W}_1-100\right) 1000=\mathrm{Q}_2+100 \mathrm{Q}_2=900 \mathrm{~J}$.
$\Delta \mathrm{U}=\mathrm{Q}_1-\mathrm{W}_1=\mathrm{Q}_2-\mathrm{W}_2$
$1000-\mathrm{W}_1=\mathrm{Q}_2-\left(\mathrm{W}_1-100\right) 1000=\mathrm{Q}_2+100 \mathrm{Q}_2=900 \mathrm{~J}$.