Work done vs work on system


Moderators: Chem_Mod, Chem_Admin

Sophia_Kiessling_2L
Posts: 61
Joined: Fri Sep 28, 2018 12:26 am

Work done vs work on system

Postby Sophia_Kiessling_2L » Tue Feb 12, 2019 10:04 pm

I know that there can either be work done on the system or work done by the system but I can't remember which one is positive and which one is negative when being calculated?

David Effio 1H
Posts: 38
Joined: Wed Feb 14, 2018 3:01 am

Re: Work done vs work on system

Postby David Effio 1H » Tue Feb 12, 2019 10:16 pm

When work is done by a system, work is negative. This is because work is essentially in energy units (J or kJ), and work is how a system loses energy. Therefore, if a system does work, the system is losing that energy it had.

When work is done on a system, that energy released is absorbed by the system. Hence, work is positive when it is done on the system.

Madeline Motamedi 4I
Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

Re: Work done vs work on system

Postby Madeline Motamedi 4I » Sun Feb 17, 2019 3:30 pm

I like to think of it in terms of the system. If you're the system and you're doing work, you lose energy (negative w). If your system is doing work it's losing energy. If work is being done on the system its gaining energy.

Lasya Gudipudi 1A
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

Re: Work done vs work on system

Postby Lasya Gudipudi 1A » Sun Feb 17, 2019 3:37 pm

When work is being done on the system, w is positive, and when work is being done by the system w is negative.

Saman Andalib 1H
Posts: 73
Joined: Fri Sep 28, 2018 12:16 am

Re: Work done vs work on system

Postby Saman Andalib 1H » Sun Feb 17, 2019 4:08 pm

When it says that there is work done onto a system, the value is positive. When it says there is work done by the system, the value is negative for the system.

Hilda Sauceda 3C
Posts: 76
Joined: Fri Sep 28, 2018 12:24 am

Re: Work done vs work on system

Postby Hilda Sauceda 3C » Sun Feb 17, 2019 4:52 pm

"on" the system its positive and "by" the system its negative

mbaker4E
Posts: 69
Joined: Fri Sep 28, 2018 12:26 am

Re: Work done vs work on system

Postby mbaker4E » Sun Feb 17, 2019 5:37 pm

When work is done on a system, or by the environment, energy is added to the system and is thus positive. when work is being done by the system, energy is being used by the system and is thus negative.

Selina Bellin 2B
Posts: 62
Joined: Fri Sep 28, 2018 12:25 am

Re: Work done vs work on system

Postby Selina Bellin 2B » Sun Feb 17, 2019 6:31 pm

work done by system is negative. its putting energy into something else aka its losing energy. and vice versa

Gisselle Sainz 2F
Posts: 76
Joined: Wed Feb 21, 2018 3:00 am

Re: Work done vs work on system

Postby Gisselle Sainz 2F » Sun Feb 17, 2019 10:13 pm

When work is done on the system, work is positive.
When the system does work, work is negative.

Shibhon_Shepard
Posts: 62
Joined: Wed Nov 15, 2017 3:04 am

Re: Work done vs work on system

Postby Shibhon_Shepard » Tue Feb 19, 2019 9:17 pm

Think about it in terms of yourself.
if you're doing a workout, you lose energy.
But if someone else is doing it, you're positive energy.

Ricardo Martin 1J
Posts: 63
Joined: Fri Sep 28, 2018 12:15 am

Re: Work done vs work on system

Postby Ricardo Martin 1J » Wed Feb 20, 2019 9:20 am

When work is done BY the system w is negative and when work is done ON the system w is positive.

Sapna Ramappa 1J
Posts: 63
Joined: Fri Sep 28, 2018 12:24 am

Re: Work done vs work on system

Postby Sapna Ramappa 1J » Sat Mar 09, 2019 8:38 am

When work is done on a system, the work has a positive value. When work is done by a system, the work has a negative value.

Nicolle Fernandez 1E
Posts: 56
Joined: Fri Sep 28, 2018 12:25 am
Been upvoted: 1 time

Re: Work done vs work on system

Postby Nicolle Fernandez 1E » Mon Mar 11, 2019 3:54 pm

When the system is doing work it loses energy which makes it negative, while if the system has work done on it it gains energy and its a positive value.

Mark 1D
Posts: 63
Joined: Fri Sep 28, 2018 12:18 am

Re: Work done vs work on system

Postby Mark 1D » Mon Mar 11, 2019 8:07 pm

work done by the system is negative, work done on the system is positive

Jacqueline Duong 1H
Posts: 61
Joined: Fri Sep 28, 2018 12:28 am

Re: Work done vs work on system

Postby Jacqueline Duong 1H » Sun Mar 17, 2019 4:53 am

When work is being done ON the system, work is positive. When work is being done BY the system, work is negative since it is losing energy.

Claudia Luong 4K
Posts: 59
Joined: Fri Sep 28, 2018 12:25 am

Re: Work done vs work on system

Postby Claudia Luong 4K » Sun Mar 17, 2019 10:53 am

I believe the way we've been doing in class is work done by the system is negative and work done on a system is positive.

Gillian Ward 1F
Posts: 61
Joined: Fri Sep 28, 2018 12:27 am

Re: Work done vs work on system

Postby Gillian Ward 1F » Sun Mar 17, 2019 2:41 pm

Work done on the system is positive while work done by the system is negative

Isabelle Fontanilla 1I
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

Re: Work done vs work on system

Postby Isabelle Fontanilla 1I » Sun Mar 17, 2019 2:54 pm

Work done by the system results in a loss of energy from the system. This means that the internal energy is decreasing due to work. As a result, work is negative. Work being done on the system by outside forces means that energy is being inputted into the system. This makes the work positive.

Helen Mejia 1I
Posts: 67
Joined: Fri Sep 28, 2018 12:24 am

Re: Work done vs work on system

Postby Helen Mejia 1I » Sun Mar 17, 2019 10:15 pm

work being done on the system is positive while work being done by the system is negative.


Return to “Concepts & Calculations Using First Law of Thermodynamics”

Who is online

Users browsing this forum: No registered users and 3 guests