Intake Temperature for a 40.2% Efficient Carnot Engine

AI Thread Summary
The discussion revolves around calculating the intake temperature for a Carnot engine with a given exhaust temperature of 401°C and an efficiency of 40.2%. The correct formula to use is e = 1 - Tc/Th, where temperatures must be in Kelvin. The initial calculation incorrectly attempted to derive Tc from Th, leading to confusion. The correct approach is to first convert the exhaust temperature to Kelvin, then rearrange the formula to find the intake temperature. The final intake temperature, after proper calculations, is approximately 130.052°C.
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Homework Statement


The exhaust temperature of a Carnot heat engine is 401◦ C.
What is the intake temperature if the efficiency of the engine is 40.2 %?
Answer in units of ◦ C.


Homework Equations



e = 1 - Tc/Th (all in Kelvin)


The Attempt at a Solution


0.402 = 1 - Tc/ (401+273) = 1 - Tc/674
Tc = 0.598 * 674 = 403.052
Tc in C = 403.052-273 = 130.052

But somehow this answer seems to be wrong on the quest. This is my last problem ..please help? What am I doing wrong? Am I missing something?
 
Physics news on Phys.org
You were given Tc to get Th, not the other way around like you did.
 
Thanks .. that worked.
 

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