## Using Derivative/Integral Equations

$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$

Sophia Diaz - Dis 1B
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Joined: Fri Apr 06, 2018 11:02 am
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### Using Derivative/Integral Equations

I don't fully understand when and where we are supposed to use these "$\int$' equations. Are we actually supposed to use them to solve problems or did we just go over them in order to show where the other equations came from?

Also how do you know how these equations change depending on what is constant? (pressure, temperature, etc)

Rachana Jayaraman 1H
Posts: 61
Joined: Fri Sep 28, 2018 12:26 am

### Re: Using Derivative/Integral Equations

The integrals were used to show how the equations for work were derived.
The actual equations you need to know are w = -PdeltaV and w = -nrtln(V2/V1). The first equation is used under constant pressure and the second is used for isothermal expansion (constant temperature).
When volume is constant, w = 0 since there is no expansion or contraction occurring.

Jonathan Omens 1K
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Joined: Fri Sep 28, 2018 12:15 am

### Re: Using Derivative/Integral Equations

You won't have to integrate to solve any problems. They were just used to derive others from class.
As for knowing which equations to use when certain values are constant, you just have to remember which to use in which scenario.

Ronald Thompson 1F
Posts: 59
Joined: Fri Sep 28, 2018 12:25 am

### Re: Using Derivative/Integral Equations

You will not need to solve integrations. Just know what equations you get from the integrations. Those are applicable to different questions and the circumstances

AnnaYan_1l
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### Re: Using Derivative/Integral Equations

I think the integrals are just used to understand why the equations were were given in class make sense!

Kriti Goyal 4K 19
Posts: 32
Joined: Fri Sep 28, 2018 12:21 am

### Re: Using Derivative/Integral Equations

The integrals are only for derivations. We . wont be asked to derive the equations, only to use them in solving problems

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