Thermal Radiation Homework: Ranking Objects of Same Material

AI Thread Summary
The discussion centers on ranking three solid objects—cube, sphere, and hemisphere—made of the same material and maintained at a temperature of 350K in a 300K environment based on their thermal radiation exchange rates. The participants consider whether to rank the objects by surface area, as larger surface areas typically result in higher rates of thermal radiation exchange. The Stefan-Boltzmann law (E=AσT^4) is highlighted as essential for justifying the ranking, indicating that the net radiation exchange is proportional to surface area and the fourth power of temperature difference. The importance of justifying the order based on these principles is emphasized. Understanding these concepts is crucial for accurately solving the homework problem.
tjr39
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Homework Statement



Consider the following three solid object all made of the same material;
1) Cube of edge length r
2) Sphere of radius r
3) Hemisphere of radius r

All object are maintained at a temperature 350K in an envorinment at temperature 300K. Rank the objects according to the net rate at which they exchange thermal radiation with the environment. Justify for full marks.

Homework Equations





The Attempt at a Solution



Im not sure whether to list them simply in order of surface area or not? Is there something else I should be considering? Cheers.
 
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tjr39 said:
Im not sure whether to list them simply in order of surface area or not? Is there something else I should be considering? Cheers.

So if you list them in terms of surface area, why would you justify it to be in that order?

Even though you have the correct idea, you should know this formula E=A \sigma T^4 (Stefan's law of black body radiation)
 

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