First Law Concept


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nelms6678
Posts: 53
Joined: Fri Sep 29, 2017 7:07 am

First Law Concept

Postby nelms6678 » Mon Jan 22, 2018 11:07 am

I know that it is true for a closed system the internal energy changes as a function of heat & work, however, what about an open or isolated system? How does the first law apply to these two other systems?

Sohini Halder 1G
Posts: 58
Joined: Thu Jul 13, 2017 3:00 am
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Re: First Law Concept

Postby Sohini Halder 1G » Mon Jan 22, 2018 11:25 am

Dr. Lavelle mentioned that the change in internal energy of a isolated system is 0, because neither mass or energy can leave the system and therefore Delta U is = 0.

Nisarg Shah 1C
Posts: 54
Joined: Sat Jul 22, 2017 3:00 am

Re: First Law Concept

Postby Nisarg Shah 1C » Mon Jan 22, 2018 11:59 am

The first law talks about the conservation of energy, so therefore it makes sense that in an isolated system, the change in internal energy is 0. However, in open and closed systems, internal energy can change, because matter and energy or just energy can be exchanged between the system and its surroundings.

Andrea ORiordan 1L
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Re: First Law Concept

Postby Andrea ORiordan 1L » Mon Jan 22, 2018 12:26 pm

We use the first law a lot in class-- it applies to open and closed systems as well as isolated systems in the way that energy cannot be created or destroyed. If an open or closed system loses energy, that energy is transferred to the surroundings-- it doesn't just disappear. Hope that helps!

Tim Nguyen 2J
Posts: 31
Joined: Sat Jul 22, 2017 3:00 am

Re: First Law Concept

Postby Tim Nguyen 2J » Mon Jan 22, 2018 2:57 pm

The first law is basically conservation of energy (energy is neither created nor destroyed). The more practical application of the law that we have been using is delta U = q+w


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