Carnot Engine Question: Efficiency & Work/Heat Rejected

AI Thread Summary
The discussion revolves around a Carnot heat engine operating between two temperature reservoirs, absorbing heat at 1200K and rejecting it at 400K. The efficiency of the engine is calculated to be approximately 66.67%. When the engine absorbs 2400J of heat, the work done is determined to be 1600J, with 800J of heat rejected. The calculations align with the principles of thermodynamics, confirming the understanding of the material. Overall, the participant expresses satisfaction with their reasoning and comprehension of the topic.
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Homework Statement



A Carnot heat engine absorbs heat form a high-temp reservoir at 1200K and concerts some of it into useful work and rejects the rest to a low-temp reservoir at 400K. A) What is the efficiency of the engine? b) If the engine absorbs 2400J per cycle from the high-temp reservoir at 1200K, what is the amount of work done, and how much heat is rejected to the low-temp reservoir at 400K?

Homework Equations



A) e = (T2-T1)/T2
ΔU=Q-W

The Attempt at a Solution



For part a, I got (1200-400)/1200= 0.6666...

For part b, my logic is that Total energy = work + heat rejected, based on ΔU formula above.
Therefore, work done should be 2400J*0.66 = 1600 J and heat rejected should be the rest, aka 2400*0.33 = 800J.

These answers seems to easy, especially for part b. Am I doing something wrong?
 
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Well done. Sometimes physics is easy - with that reasoning it sounds like you have understood the material.
 
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Simon Bridge said:
Well done. Sometimes physics is easy - with that reasoning it sounds like you have understood the material.

Thanks for the confirmation.
 
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