Isobaric System (work done by, or on?)

  • Thread starter audilover
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  • #1
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Homework Statement



There is a graph PxV. Pressure is obviously constant so it is a strait line and volume is from point A (1) to point B (3.5). You do not need to solve anything but it asks if work is being done on the system or by the system.

Homework Equations



U=Q-W

The Attempt at a Solution



I thought work is being done on the system because when going from point A to point B you are increasing meaning your Q>0.
 

Answers and Replies

  • #2
vela
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Going from point A to point B, you are increasing what? Also, Q has nothing to do with whether work is being done on or by the system. Even if you solve this problem based on what I wrote below, it might be worth explaining what you were thinking originally. I'm guessing you have a common misconception that may be worth clearing up.

All you need to do for this problem is figure out the sign of W. If W>0, the work is subtracting from the internal energy U of the system, so work is being done by the system on its surroundings. Similarly, if W<0, work is done on the system.
 

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