Physics thermodynamics equation

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SUMMARY

The discussion revolves around solving a thermodynamics problem involving a monatomic ideal gas, where the pressure doubles and the volume triples. The user calculated the work done by the gas as 3(Vi)(Pi) and the change in internal energy as (15/2)(Pi)(Vi). However, they encountered an issue with WebAssign interpreting "Pi" as the mathematical constant π instead of the variable for initial pressure. The solution was to use "P_i" to denote the initial pressure correctly.

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  • Understanding of the ideal gas law (PV=nRT)
  • Familiarity with thermodynamic equations for work and internal energy
  • Knowledge of calculus for integrating pressure-volume graphs
  • Basic understanding of WebAssign and variable notation
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  • Review the ideal gas law and its applications in thermodynamics
  • Study the derivation of work done by gases in various processes
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Students studying thermodynamics, physics educators, and anyone working with ideal gas equations and online homework platforms.

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Homework Statement


A certain amount of a monatomic ideal gas undergoes the process shown in the figure below, in which its pressure doubles and its volume triples.

18-26.gif


In terms of the number of moles, n, the initial pressure, Pi, and the initial volume, Vi, determine the quantities tabulated below. Use n, Pi, and Vi to represent n, Pi, and Vi, respectively.

(a) work W done by the gas
(b) change in the internal energy U of the gas
(c) heat Q added to the gas



Homework Equations



W=integral of graph... lol
T=PV/nR
Change in Eint=(3/2)nRT

The Attempt at a Solution



ok i worked out (a) to be 3(Vi)(Pi) by finding the integral (area under the graph) and (b) to be (15/2)(Pi)(Vi) by finding the difference in temperatures and putting them in the energy equation (having the R value and n value cancel out). I'm fairly certain I am correct, but webassign says that they are wrong. The only reason I can think of why is because webassign treats the (Pi) as the greek Pi 3.14159 number, but I've been entering it the way it says.


Can someone confirm this with me/tell me why its treating it as pi?
 

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nvm i had to put P_i and not Pi lol
 

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