Having problems with a thermo. cycle

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SUMMARY

The discussion focuses on solving a thermodynamic cycle involving processes A->B (isobaric), B->C (adiabatic), C->D (isothermal), and D->A (isochoric). The user consistently calculates temperatures for states B and C as 2.44x10^4 K, which is incorrect. The key error lies in the assumption that the temperature of B is the same as A during the isobaric process. Correct application of the ideal gas law and consistent unit checks are crucial for accurate calculations.

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  • Understanding of thermodynamic processes (isobaric, adiabatic, isothermal, isochoric)
  • Proficiency in the ideal gas law (PV=nRT)
  • Ability to perform unit conversions and ensure consistency
  • Familiarity with temperature calculations in thermodynamic cycles
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  • Review the ideal gas law applications in thermodynamic cycles
  • Study the implications of isobaric processes on temperature and volume
  • Learn about common pitfalls in thermodynamic calculations
  • Explore alternative methods for solving thermodynamic problems
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This discussion is beneficial for students and professionals in thermodynamics, particularly those studying or working with heat engines and refrigeration cycles.

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Having problems with a thermo. cycle!

OK, so in the problem A->B is isobaric, B->C is adiabatic, C->D is isothermal, D->A is isochoric.

Pa = 2atm, Va = 2 m^3, n = 1mole, Vb = 1/2Va, Pa = 2Pd (That is all the information that is given.)

I always end up with the temperatures of B and C both equaling 2.44x10^4 K. What am I doing wrong?

(After I did all the calculations for A->B, I went over to D since there was no info for C in the problem. After finding the temperature of D, I found the temperature of C since C->D is isothermal. I found the temperature at D by assuming that Va = Vd since it is an isochoric process, and also since Pa=2Pd due to what is given in the problem. So then I used PV=nRT at D to find the temp there.
 
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Then I found the temp of C, since C->D is isothermal. After that, I found the temp of B by using the ideal gas law at B, but it's not working out quite right.) The problem you are having is likely because you are making an incorrect assumption about the process A->B. If this process is isobaric, then the temperature of B should be the same as the temperature of A. Therefore, you should use the temperature of A to calculate the volume of B, and then use the ideal gas law to calculate the temperature of C.
 
Then I went back to C and used the ideal gas law to find the temperature there.)

It seems like you have the right approach in solving this problem. However, there could be a mistake in your calculations or in the values given. It would be helpful if you could provide your calculations or show your work so that we can identify where the error might be. Also, it is important to check your units and make sure they are consistent throughout your calculations. Sometimes, small unit errors can lead to significant differences in the final answer. Additionally, double check the values given in the problem and make sure they are accurate. If you are still having trouble, perhaps try approaching the problem from a different angle or using a different formula to solve for the temperatures. Good luck!
 

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