Negative work

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Henry_Phan_4L
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Joined: Fri Sep 28, 2018 12:24 am

Negative work

Postby Henry_Phan_4L » Sat Feb 02, 2019 7:02 pm

Can negative work be done on a system? Does increasing the volume count as negative work?

Jonas Talandis
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am

Re: Negative work

Postby Jonas Talandis » Sat Feb 02, 2019 7:06 pm

Negative Work is definitely a thing. All it means is that the system is doing work on the surroundings instead of getting work done on itself. This happens when the piston moves out for example.

MadelynNguyen1F
Posts: 59
Joined: Fri Apr 06, 2018 11:04 am

Re: Negative work

Postby MadelynNguyen1F » Sat Feb 02, 2019 8:30 pm

Yes, negative work is when work leaves the system.

Mukil_Pari_2I
Posts: 87
Joined: Fri Sep 28, 2018 12:29 am

Re: Negative work

Postby Mukil_Pari_2I » Sat Feb 02, 2019 8:36 pm

Yes, if the force being applied is in the opposite direction of the displacement, the work will be negative.

davidryan3f
Posts: 63
Joined: Fri Sep 28, 2018 12:23 am

Re: Negative work

Postby davidryan3f » Mon Feb 04, 2019 4:52 pm

Yes negative work will occur when the system does work on its surroundings rather than the surroundings doing work oil the system.

Tinisha 1G
Posts: 69
Joined: Fri Sep 28, 2018 12:17 am

Re: Negative work

Postby Tinisha 1G » Wed Feb 06, 2019 11:03 am

Negative work is represented by a system doing work on its surroundings. When work is done on system, it is positive work.

Tony Chung 2I
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

Re: Negative work

Postby Tony Chung 2I » Wed Feb 06, 2019 11:27 pm

yes, it is a thing. This will happen when system does work on the surrounding.

Jasmine Chow 1F
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Re: Negative work

Postby Jasmine Chow 1F » Thu Feb 07, 2019 11:18 pm

Yes you can have negative work on a system. An example of this would be the system doing work on its surroundings. Increasing the volume does count as negative work by the system.

EllaBerry
Posts: 68
Joined: Fri Sep 28, 2018 12:29 am

Re: Negative work

Postby EllaBerry » Fri Feb 08, 2019 8:56 pm

Yes, negative work is done when a system does work on its surroundings.

madisondesilva1c
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Re: Negative work

Postby madisondesilva1c » Fri Feb 08, 2019 9:04 pm

If the work is negative, how would the isobaric work equation change? Would the integral now be of a positive quantity instead of a negative one?

Vincent Li 4L
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Joined: Fri Sep 28, 2018 12:19 am

Re: Negative work

Postby Vincent Li 4L » Fri Feb 08, 2019 9:47 pm

madisondesilva1c wrote:If the work is negative, how would the isobaric work equation change? Would the integral now be of a positive quantity instead of a negative one?


For an isobaric expansion/compression, the pressure is constant (isobaric: deltaP = 0), so the we would use the equation w = -P*deltaV. If the change in volume is positive, then the total value will be negative. If we're talking in terms of the integral, you are correct in saying it would then be a positive quantity. Since the equation has ln(Vf/Vi), where Vf is final volume and Vi is initial volume, this means that any time a gas expansion occurs, the final volume will be greater than the initial volume. This makes the natural log of their ratio a positive value, and because there is also a negative sign in the equation, work will then be negative.

Megan_Ervin_1F
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Joined: Fri Sep 28, 2018 12:18 am

Re: Negative work

Postby Megan_Ervin_1F » Sun Feb 10, 2019 7:52 pm

If the work is negative that means the system DID the work so it lost the energy as work

if the work was positive that means that work was done ON the system so it gained energy as work


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