How to Calculate Efficiency and Heat Rejection in an Engine?

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Homework Help Overview

The discussion revolves around calculating the efficiency and heat rejection of an engine based on given energy values. The problem is situated within the context of thermodynamics, specifically focusing on energy transfer and efficiency calculations in cyclic processes.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the definition of efficiency and its calculation using the formula involving work done and energy absorbed. Questions arise regarding the calculation of heat rejected, with some suggesting it may be the leftover energy after work is done.

Discussion Status

Some participants have provided guidance on the efficiency calculation, while others are seeking clarification on the heat rejection aspect. There is an ongoing exploration of the concepts involved, with no explicit consensus reached on the complete understanding of the problem.

Contextual Notes

Participants express confusion regarding the calculations and the application of the first law of thermodynamics, indicating a need for further clarification on these principles.

jin
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heat system efficiency??

So lost..so what am i suppose to do??

'An engine absorbs 400J of heat and does 120J of work in each cycle'

a)what is its efficiency?
b)how much heat is rejected in each cycle?
 
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For a cycle, that is, when after a process, a system comes back to its original state, the difference of the net energy taken and work done by it is zero - first law of thermodynamics.

[tex]Efficiency = \frac{work done}{energy taken}[/tex]


spacetime
www.geocities.com/physics_all/index.html
 
so...i just go 120/400 x 100?

how do i calculate th heat rejected in the cycle?? the left over? 400-120??
 
correct!

spacetime
 
thanks! can u help me with the others on another post?? please ><
 

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