Thermodynamics Help: Ideal Gas Temperature Rise Comparison

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Homework Help Overview

The discussion revolves around a thermodynamics problem involving two cylinders containing an ideal monoatomic gas at a specified temperature. The cylinders are subjected to the same amount of heat energy, but one piston is free to move while the other is fixed. Participants are exploring the implications of these conditions on the temperature rise of the gases in each cylinder.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are analyzing the effects of heat transfer on the temperature changes in the two cylinders, questioning how the fixed and movable pistons influence the distribution of energy. There are discussions about the relationship between heat supplied and temperature change, particularly in terms of internal energy and work done during expansion.

Discussion Status

Some participants have suggested that the temperature rise in the fixed piston scenario should be greater due to the complete conversion of heat into internal energy, while others are questioning this assumption and exploring the ratio of specific heats in relation to the temperature changes. There is no explicit consensus on the correct temperature rise for cylinder B, but various interpretations and calculations are being discussed.

Contextual Notes

The problem involves assumptions about the behavior of ideal gases and the specific heat capacities, which are central to the discussion. Participants are also navigating the implications of the problem's setup, such as the constraints imposed by the fixed and movable pistons.

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Homework Statement



Two cylinders A and B fitted with pistons contain equal number of moles of an ideal monoatomic gas at 400K. The piston of A is free to move while that of B is held fixed. Same amount of heat energy is given to the gas in each cylinder. If the rise in temperature of the gas in A is 42K, the rise in temperature of the gas in B is

a)21K
b)35K
c)42K
d)70K

The Attempt at a Solution



Going by the options, the answer should be d) because the entire heat supplied is used to raise the internal energy of the gas in container B where as some part of it is used to do work against the piston in container A (work on expansion). But this is incorrect.
 
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Abdul Quadeer said:

Homework Statement



Two cylinders A and B fitted with pistons contain equal number of moles of an ideal monoatomic gas at 400K. The piston of A is free to move while that of B is held fixed. Same amount of heat energy is given to the gas in each cylinder. If the rise in temperature of the gas in A is 42K, the rise in temperature of the gas in B is

a)21K
b)35K
c)42K
d)70K

The Attempt at a Solution



Going by the options, the answer should be d) because the entire heat supplied is used to raise the internal energy of the gas in container B where as some part of it is used to do work against the piston in container A (work on expansion). But this is incorrect.
d) is the correct answer. The ratio of the temperature of B to that of A is Cp/Cv = 5/3. 5x42/3 = 70

AM
 


Thanks!
 


Andrew Mason said:
d) is the correct answer. The ratio of the temperature of B to that of A is Cp/Cv = 5/3. 5x42/3 = 70
I meant to say of course that the ratio of the "change in" temperature of B to that of A is Cp/Cv.

AM
 

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