Question

If the ratio of specific heat of a gas at constant pressure to that at constant volume is $\gamma$ , the change in internal energy of a mass of gas, when the volume changes from V to 2V constant pressure p, is

• A. $R / ( \gamma - 1 )$
• B.
• C. $p V / ( \gamma - 1 )$
• D.

Answer 1

Answer: (C)

$p V / ( \gamma - 1 )$

Answer 2

$\Delta U = \mu C _ { V } \Delta T = n \left( \frac { R } { \gamma - 1 } \right) \Delta T$

$\Rightarrow \Delta U = \frac { P \Delta V } { ( \gamma - 1 ) } = \frac { P ( 2 V - V ) } { \gamma - 1 } = \frac { P V } { ( \gamma - 1 ) }$