## Work equation

$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$

Katie Clark 3B
Posts: 26
Joined: Fri Sep 25, 2015 3:00 am

### Work equation

Why is there a negative in the work equation w=-PΔV?

Ranger Saldivar 2D
Posts: 28
Joined: Fri Sep 25, 2015 3:00 am

### Re: Work equation

If you are expanding a gas by a constant external pressure to match the positive difference in $\Delta$V you need to account for the loss in work by putting a negative sign in front of the equation.

KendraArriaga 1F
Posts: 10
Joined: Fri Sep 25, 2015 3:00 am

### Re: Work equation

When a gas expands, it does work against the lid that contains it - the gas is "pushing" against the lid and is ultimately losing energy. Therefore, the negative sign is incorporated into the equation to show that its expansion represents a loss of energy.