Solve Thermodynamics Problem: Change in Temp w/ Volume, Power & Specific Heat

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    Thermodynamics
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Discussion Overview

The discussion revolves around a thermodynamics problem involving the calculation of temperature change in an isochoric process given specific parameters such as volume, specific heat, initial temperature, atmospheric pressure, and the power of a heater. The focus is on understanding how to derive the change in temperature from the provided information.

Discussion Character

  • Homework-related

Main Points Raised

  • One participant expresses confusion about calculating the change in temperature, noting the relationship between heat and specific heat at constant volume (Cv).
  • Another participant clarifies that the temperature change can only be expressed as a rate (e.g., "temperature increased by ... °C per second") rather than a total change without a specified time frame.
  • A participant questions how to calculate the change in heat with the given data, indicating a need for additional information or assumptions.
  • There is a suggestion that looking up internal energy values from a superheated table and interpolating may be necessary to find the initial internal energy.
  • Reiteration of the challenge in calculating heat change without assuming a specific time period.

Areas of Agreement / Disagreement

Participants do not reach a consensus on how to calculate the change in heat or temperature without additional assumptions, particularly regarding the time factor involved.

Contextual Notes

The discussion highlights limitations related to the assumptions required for calculations, particularly the need for a defined time period to determine temperature change accurately.

tigertan
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Homework Statement



I'm getting a bit stuck with this problem..

Given a volume, it's specific heat at constant volume, an initial temperature, pressure (atmospheric) and the power of a heater within this volume, I am expected to calculate the change in temperature for the body.

Homework Equations


I understand that Cv=du/dT. I also understand that the volume doesn't change as it is an isochoric process.


We get dT= dq/Cv=du/Cv. I don't understnad how to get the heat value. I've converted the power of the heater from Watts to Joules per hour..
 
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From the data given you can calculate temperature change per time unit only (so you can say "temperature increased by ... °C per second", but not "temperature increased by ... °C").
 
how can i calculate the change of heat though, wiht what has been given to me?
 
am I expected to look up the internal energy on a superheated table and interpolate across to find the first internal energy?
 
tigertan said:
how can i calculate the change of heat though, wiht what has been given to me?

You can't without assuming some period of time.
 

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