Work Calculation

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Sophie Roberts 1E
Posts: 61
Joined: Fri Sep 28, 2018 12:17 am

Work Calculation

Postby Sophie Roberts 1E » Thu Jan 31, 2019 4:07 pm

I remember Lavelle going over this but couldn't remember his explanation... why must the constant pressure have a negative sign in front for the calculation of work done on a system?

Alana Sur 3B
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am

Re: Work Calculation

Postby Alana Sur 3B » Thu Jan 31, 2019 4:18 pm

I think it's because the system loses energy

Neil Hsu 2A
Posts: 61
Joined: Fri Sep 28, 2018 12:16 am

Re: Work Calculation

Postby Neil Hsu 2A » Thu Jan 31, 2019 5:20 pm

There must be a negative sign since our system is the gas inside the piston. When we compress the gas, we do work on the gas and increase its internal energy. However, the final volume minus the initial volume would give us a negative number (because the gas is compressed). Without a negative sign, our value would be negative, implying that work is done by the system, where in fact, work is done on the system. Therefore, we need a negative sign to give us the right direction of work.

005113695
Posts: 59
Joined: Fri Sep 28, 2018 12:15 am

Re: Work Calculation

Postby 005113695 » Sat Feb 02, 2019 1:59 pm

the negative sign tells us whether the system is doing work or if work is being done on they system


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