Work Done in a polytropic process

AI Thread Summary
In a polytropic process with n=1, the work done by a gas in a cylinder-piston arrangement can be calculated using the equation W = P1 * V1 * ln(V2/V1). The initial conditions are a pressure of 13,789.5 Pa and a volume increase from 0.02832 m^3 to 0.08496 m^3. The integral for work involves expressing pressure as a function of volume, which simplifies due to the nature of n=1. Participants in the discussion confirm that the approach is correct and express gratitude for guidance on the calculations. The thread emphasizes the importance of understanding the integral derivation for accurate results in thermodynamic processes.
juggalomike
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Homework Statement


A gas is trapped in a cylinder-piston arrangement. The initial pressure and volume are 13,789.5 Pa and 0.02832 m^3. Determine the work(kj) assuming that the volume is increased to 0.08496 m^3 in a polytropic process with n=1.


Homework Equations


m_1-2=∫PdV from 1 to 2


The Attempt at a Solution



I believe the equation for n=1 i would use is P1*V1*ln(V2/V1), however i have to show how i would get that from the intial integral, and i am completely lost as to how i can get there.

Also if this is not the correct forum for this post i am sorry, please let me know and i will
re-post it in the correct location.
 
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The ln term comes about because the integral of 1/x is ln(x).
Search wikibooks for polytropic process.
 
juggalomike said:

Homework Statement


A gas is trapped in a cylinder-piston arrangement. The initial pressure and volume are 13,789.5 Pa and 0.02832 m^3. Determine the work(kj) assuming that the volume is increased to 0.08496 m^3 in a polytropic process with n=1.


Homework Equations


m_1-2=∫PdV from 1 to 2


The Attempt at a Solution



I believe the equation for n=1 i would use is P1*V1*ln(V2/V1), however i have to show how i would get that from the intial integral, and i am completely lost as to how i can get there.

Also if this is not the correct forum for this post i am sorry, please let me know and i will
re-post it in the correct location.
Express P as a function of V and integrate. Since n=1 in PV^n = K, this is rather simple.

AM
 
Andrew Mason said:
Express P as a function of V and integrate. Since n=1 in PV^n = K, this is rather simple.

AM

Thanks a lot, knew it wasn't a hard question was just stuck on the sub part.
 
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