## Equation for Work

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

Ellis Song 4I
Posts: 102
Joined: Thu Jul 11, 2019 12:17 am

### Equation for Work

Is the equation for work always negative even if we are calculating work done on the system?

705302428
Posts: 50
Joined: Sat Aug 24, 2019 12:16 am

### Re: Equation for Work

Yes I think so.

Michael Nguyen 1E
Posts: 120
Joined: Sat Aug 17, 2019 12:17 am

### Re: Equation for Work

Yes, the equation will still have a negative sign in front. When work is done on the system, the change in volume is negative. This negative cancels with the one in the equation, resulting in a positive value for work. This makes sense because when work is done on the system, the value should be positive.

Pegah Nasseri 1K
Posts: 100
Joined: Wed Feb 27, 2019 12:15 am

### Re: Equation for Work

Yes, when calculating the work always use the equation W = - (P*deltaV) and make sure to include the negative sign. If work is done on the system, then you know a compression will occur which means the volume will decrease. If the volume decreases due to compression, then the change in volume will be negative since the smaller final volume is subtracted by the larger initial volume. The negative change in volume when plugged into the equation will cancel out the negative sign in the equation, making the calculated value of the work positive.