Question

A gas is compressed from a volume of $2m^3$ to a volume of $1m^3$ at a constant pressure of $100N/m^2$. Then it is heated at constant volume by supplying $150J$ of energy. As a result, the internal energy of the gas :

• A. Increases by $250J$
• B. Decreases by $250J$
• C. Increases by $50J$
• D. Decreases by $50J$

Answer 1

The correct option is A Increases by $250J$

$\Delta U=Q+W$
$\Delta U=Q+P\Delta V$
$\therefore \Delta U=150+100(2-1)$
$\therefore \Delta U=250$

As the value is positive, internal energy of the gas increases by $250J$