Question

$3000\text{J}$ of heat is given to a gas at constant pressure of $2\times {10}^5{\text{N/m}}^2$ If its volume increases by $10$ litres during the process find the change in the internal energy of the gas.

• A. $-1000\text{J}$
• B. $1000\text{J}$
• C. $-2000\text{J}$
• D. $2000\text{J}$

Answer 1

The correct option is B $1000\text{J}$

Heat given to the system $△Q=3000\text{J}$
pressure applied = $2\times {10}^5{\text{N/m}}^2)$
$W=P△V=(2\times {10}^5{\text{N/m}}^2)(10\times {10}^{-3}{\text{m}}^3)$
$=2\times {10}^3\text{J}$
from first law of thermodynamic,
$△U=△Q-W=3000-2000=1000\text{J}$