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### Integral

Posted: **Thu Jan 30, 2020 9:40 am**

by **Diana_Diep2I**

Will we be using the integral equation? When will we use w=-P∆V and when will we use the integral? What is the difference between them? Is it because in the integral, external pressure may not be constant?

### Re: Integral

Posted: **Thu Jan 30, 2020 9:46 am**

by **Izzie Capra 2E**

I believe Lavelle will simplify the integral equation next lecture. In the textbook, there is an equation that is much easier to work with--I believe he will be discussing that. This one was used when discussing reversible, isothermal expansion reactions: the ones done in small steps (hence the integral). P is constant but volume is changing. Expansion of gas held at constant pressure is represented by the equation w=p times delta v.

### Re: Integral

Posted: **Thu Jan 30, 2020 10:11 am**

by **Leonardo Le Merle 1D**

I also had confusion with this part of the lecture as I'm currently in Math 3B and we haven't covered integrals yet; if someone could clarify what exactly v1{v2 means that'd be great.

### Re: Integral

Posted: **Thu Jan 30, 2020 10:38 am**

by **Bryce Barbee**

I dont think that we will use the integral equation. I think it is more to show that the Wby is equation to the area under a graph of pressure vs volume.

### Re: Integral

Posted: **Thu Jan 30, 2020 12:00 pm**

by **Anisha Chandra 1K**

I think you should just know that an integral is used to sum a series of steps, and in this case infinitesimal changes. It's basically the area under a curve, so the reason we use it to sum up infinitesimal changes is so we can sum the change in a pressure/volume curve.