Question

The first law of thermodynamics can also be represented as $\Delta U=q-P\Delta V$

• A. True
• B. False

Answer 1

The correct option is A

True

The first law of thermodynamics is represented by $\Delta U=q+w$

But $w=F\times L(Force\times Displacement)$

$w=-PA\times L=-P\times AL(ButAL=\Delta V)$
Negative sign is because of Force and displacement are of opposite direction.

$\therefore w=-P\Delta V$

$\therefore$ For work done by the system $\Delta U=q-P\Delta V$