Question

The gas is heated at a constant pressure. The fraction of heat supplied used for external work is

• A. $\frac{1}{\gamma }$
• B. $(1-\frac{1}{\gamma })$
• C. $\gamma -1$
• D. $(1-\frac{1}{{\gamma }^2})$

Answer 1

Answer: (B)

$(1-\frac{1}{\gamma })$

Heat absorbed =$\Delta Q=n{C}_p\Delta T=\gamma n{C}_v\Delta T$
Internal energy change=$\Delta U=n{C}_v\Delta T$

Work done=$\Delta Q-\Delta U=(\gamma -1)n{C}_v\Delta T$
Required fraction$=\frac{\gamma -1}{\gamma }=1-\frac{1}{\gamma }$