Question

A sample of ideal gas (g = 1.4) is heated at constant pressure. If an amount of 100 J heat is supplied to the gas, the work done by the gas is:

• A. 42.12 J
• B. 56.28 J
• C. 28.57 J
• D. 36.23 J

Answer 1

Answer: (C)

28.57 J

Answer 2

nCpDT = 100 J

$n\left( \frac{\gamma R}{\gamma - 1} \right)\Delta T = 100J$, nRDT = $\left( 100 \times \frac{\gamma - 1}{\gamma} \right)$

W = nRDT = 100 × $\frac{0.4}{1.4}$