Heat energy of $735 \mathrm{~J}$ is given to a diatomic gas allowing the gas to expand at constant pressure. Each gas molecule rotates around an internal axis but do not oscillate. The increase in the internal energy of the gas will be :
Solution
$\Delta Q=n C_{P} \Delta T= $
<br/><br/>$n\left( {{f \over 2} + 1} \right)R\Delta T$
<br/><br/>= $n\left( {{5 \over 2} + 1} \right)R\Delta T$
<br/><br/>= $n\left( {{7 \over 2}} \right)R\Delta T$
<br/><br/>Given, $\Delta Q$ = 735
<br/><br/>$\Rightarrow$ $n\left( {{7 \over 2}} \right)R\Delta T$ = 735
<br/><br/>$\Rightarrow$ $nR\Delta T = 735 \times {2 \over 7}$
<br/><br/>Also, $\Delta$U = ${f \over 2}nR\Delta T$
<br/><br/>= ${5 \over 2}nR\Delta T$
<br/><br/>= ${5 \over 2} \times 735 \times {2 \over 7}$
<br/><br/>= 525 J
About this question
Subject: Physics · Chapter: Thermodynamics · Topic: Zeroth and First Law
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