Carnot engine rejected heat problem

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Homework Help Overview

The problem involves two Carnot engines, where the first engine (A) operates between a hot reservoir at temperature T1 and a cold reservoir at 503K, taking in 5550J of heat and delivering 1750J of work. The rejected heat from engine A serves as the input for the second engine (B), which also delivers 1750J of work while rejecting heat to a colder reservoir at temperature T2. The task is to find the temperatures T1 and T2.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to apply the efficiency equations for Carnot engines but encounters difficulty determining the input heat for engine B. Some participants clarify that the input heat for engine B is the rejected heat from engine A, prompting further questions about the application of conservation of energy.

Discussion Status

Participants are exploring the relationship between the two engines and discussing the implications of conservation of energy. There is a focus on understanding how to equate input and output energies, but no consensus has been reached on the next steps or specific calculations.

Contextual Notes

The original poster expresses uncertainty about the input heat for engine B and how to proceed with the conservation of energy principle, indicating a potential gap in understanding the setup of the problem.

Nimbalo
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Homework Statement


From the hot reservoir at a temperature of T1, Carnot Engine A takes an input heat of 5550J, delivers 1750J of work and rejects heat to a cold reservoir that has a temperature of 503K. This cold reservoir also serves as the hot reservoir for a second Carnot Engine, B, which uses the rejected heat from the first engine as input heat. Engine B also delivers 1750J of work, while rejecting heat to an even colder reservoir that has a temperature T2. Find T1 and T2.


Homework Equations


e=1-Tc/Th
e=W/Qh


The Attempt at a Solution



I plugged in my values into the e=1-Tc/Th and e=W/Qh equations to solve for the Th, or T1. As an answer, I got 734.3K. However, I'm missing a variable for my second Carnot engine. What is the input heat for engine B? I tried doing 734.3-503K, but that gives me answers in K and makes the equation not work. I don't know what I'm supposed to use for the input heat.
 
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Nimbalo said:
What is the input heat for engine B?

It's the same as the output heat from engine A:
... a second Carnot Engine, B, which uses the rejected heat from the first engine as input heat.

Engine A has 5550 J of input heat. Of that 5550 J energy, 1750 J is used to do work. The remaining energy has to go somewhere (conservation of energy) ...
 
so what does this mean? what do i do with the conservation of energy?
 
copitlory8 said:
what do i do with the conservation of energy?
Equate the input energy with the total output energy.
Qin = W + Qout
If you need more help with the problem, you will have to show how far you have gotten and the work you have done.
 

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