Internal Enery, heat and work/HELP

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Homework Help Overview

The discussion revolves around a problem involving an ideal gas contained in a cylinder with a movable piston. The original poster seeks to find the work done, change in internal energy, and initial and final temperatures given specific conditions and parameters.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate work and change in internal energy but expresses uncertainty about the correctness of their values and how to determine the initial and final temperatures. Some participants suggest using the ideal gas law to find the temperatures and question the sign of the work done during the gas expansion.

Discussion Status

Participants are engaging in a back-and-forth regarding the application of the ideal gas law and the implications of the work done on the internal energy. There is a focus on clarifying the relationships between pressure, volume, and temperature, with some guidance offered on how to approach the temperature calculations.

Contextual Notes

The original poster is uncertain about their calculations and the implications of the work done on the internal energy, indicating a need for further clarification on these concepts. There is also a lack of explicit consensus on the correctness of the initial calculations presented.

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Homework Statement


There's .1 mole of an ideal gas trapped in a cylinder with a movable piston.
If Pi= Pf= 5000Pa, Vi= .04 m^3, Vf= .08m^3, Q=500J,,,Find W, change in (U), Ti and Tf.

Homework Equations



change in U = Q+W
W= -p change in V

The Attempt at a Solution



W= 200J
change in U = 700J
Ti=
Tf= i don't know how to get Ti and Tf... I am not sure whether 200J and 700J are right either..
PLease help me!
Thank you!
 
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You certainly know an equation connecting P, V and T for an ideal gas.

The gas expands, is the work done on the gas positive or negative? Will this work increase or decrase the internal energy?

ehild
 
PV=nRT

Could you please explain more in detail? I don't get what you're saying:(

THanks.
 
You know P, V, n for both states of the gas, don't you? Can you calculate the temperatures?

ehild
 

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