## -w vs w

ckilkeary 2G
Posts: 68
Joined: Fri Aug 09, 2019 12:16 am

### -w vs w

Quick clarifying question: what is the difference between getting a negative value for w vs a positive value? for example, what is the difference between w=20J vs w=-20J?

Brianna Becerra 1B
Posts: 117
Joined: Fri Aug 02, 2019 12:16 am

### Re: -w vs w

When w is negative, it means that work is being done (expansion), while when it is positive, it is compression.

205405339
Posts: 77
Joined: Thu Jul 11, 2019 12:16 am

### Re: -w vs w

POV is from the system so if the system is doing work, its positive and if its having work done on it its negative

Rafsan Rana 1A
Posts: 55
Joined: Sat Aug 24, 2019 12:16 am

### Re: -w vs w

When w is negative, it means that the system is doing work, while when w is positive, it means that the system is having work done on it.

Jainam Shah 4I
Posts: 130
Joined: Fri Aug 30, 2019 12:16 am

### Re: -w vs w

Negative work indicates that the system is doing work on the surroundings so expansion work is done and the system itself is losing energy. Positive work means that the system is being compressed and the surroundings is doing work upon the system so that means its gaining energy.

005162902
Posts: 102
Joined: Wed Sep 18, 2019 12:15 am

### Re: -w vs w

w represents work. When w is negative, the system is doing work such as expanding. However, when w is positive the system is having work done to it. For example compression of an object by an outside force.

Kishan Shah 2G
Posts: 132
Joined: Thu Jul 11, 2019 12:15 am

### Re: -w vs w

Basically work is represented by "w". negative work means that the system has lost energy since it has itself done work. positive work means that the system has gained energy because something else has done work on the system.

105335337
Posts: 103
Joined: Sat Aug 24, 2019 12:15 am

### Re: -w vs w

When w is positive, work is being done on the system & when w is negative. the system is doing work. For example, today the system pushed the piston outwards, doing work on the system, making w negative.

nicole-2B
Posts: 103
Joined: Fri Aug 30, 2019 12:18 am

### Re: -w vs w

Brianna Becerra 1B wrote:When w is negative, it means that work is being done (expansion), while when it is positive, it is compression.

thanks for clarifying I have been so confused!!

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

### Re: -w vs w

the sign of w indicates whether work is being done on the system or the system is working. Remember that the sign of work is in relation to the system.

Leonardo Le Merle 1D
Posts: 56
Joined: Wed Feb 27, 2019 12:16 am

### Re: -w vs w

This can become sort of confusing as U is said to equal both Q+W and Q-W; just try to keep in mind that internal energy is lost if the system DOES work; in the first equation this would mean W is negative and in the second it would be positive. Both mean the same thing.

Astrid Lunde 1I
Posts: 103
Joined: Sat Sep 07, 2019 12:16 am

### Re: -w vs w

w is when work is being done one the system. -w is when the system is doing work.

Rodrigo2J
Posts: 102
Joined: Sat Jul 20, 2019 12:16 am

### Re: -w vs w

Work is relative to the system. If the system is doing work then it is negative and if work is being done on the system then work positive.

Orrin Zhong 4G
Posts: 51
Joined: Sat Jul 20, 2019 12:16 am

### Re: -w vs w

Negative work is work being done by the system because the system is losing energy by doing the work. Positive work is work being done on the system because the system is gaining energy from the work.

305385703
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

### Re: -w vs w

w is a change in the internal energy of a system that is caused by a physical change (as opposed to Q which is the heat). if w is positive, then energy is being put into the system (work is being done on the system.

Max Madrzyk Dis 4G
Posts: 102
Joined: Wed Sep 18, 2019 12:21 am

### Re: -w vs w

When the work is negative that means that work was done by the system but when work is positive that means that the work was done on the system.

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