## Expansion work/ Compression

aphung1E
Posts: 101
Joined: Sat Aug 24, 2019 12:15 am

### Expansion work/ Compression

for expansion do you need to include a negative sign when calculating values

Hiba Alnajjar_2C
Posts: 108
Joined: Fri Aug 09, 2019 12:17 am

### Re: Expansion work/ Compression

When expansion takes place, work is being done and is therefore negative. When compression takes place, work is positive.

kristi le 2F
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

### Re: Expansion work/ Compression

Remember that the sign for work is always in regard to the system. In expansion, the system is doing the work and is therefore losing energy so work is negative. In compression, work is being done on the system, so work will be a positive value.

Uisa_Manumaleuna_3E
Posts: 60
Joined: Wed Sep 21, 2016 2:56 pm

### Re: Expansion work/ Compression

Expansion and compression both denote work, but they exert that work in opposite directions. It helps me keep in mind the visual of a balloon expanding and deflating. Both require a change of energy or movement, but one obviously has a positive growth and the other a negative.

You just have to remember that when an object does do work (balloon expanding/expansion) that object or system LOSES that energy so its a negative.
When an object undergoes compression (balloon shrinking/compression) that object has work acted on it by something else so it GAINS energy and is positive.

Abby Soriano 1J
Posts: 103
Joined: Sat Aug 24, 2019 12:16 am

### Re: Expansion work/ Compression

Things like work and heat should always be approached from the point of view of the system. Just as when heat is being applied to a system and delta H is a positive value, when work is being done on/to a system, the value of work is positive. When the system is doing work to its surroundings, work is negative.

stephaniekim2K
Posts: 79
Joined: Fri Aug 09, 2019 12:16 am

### Re: Expansion work/ Compression

During expansion, work is being done so you need a negative sign while compression you need a positive sign.

Kennedi2J
Posts: 101
Joined: Wed Sep 18, 2019 12:20 am

### Re: Expansion work/ Compression

w = (+) when work is done on the system (compression)
w = (-) when work is done by the system (expansion)

Veronica Lu 2H
Posts: 89
Joined: Wed Sep 18, 2019 12:18 am
Been upvoted: 1 time

### Re: Expansion work/ Compression

negative work means work is being done (expansion) whereas positive work signifies work is done on the system (compression)