About Second Law of Thermodynamics

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Discussion Overview

The discussion revolves around the implications of a hot object not emitting radiation in relation to the second law of thermodynamics. Participants explore theoretical scenarios and the fundamental principles of heat transfer, entropy, and radiation absorption and emission.

Discussion Character

  • Debate/contested, Conceptual clarification, Exploratory

Main Points Raised

  • Some participants argue that if a hot object did not emit radiation, it would violate the second law of thermodynamics, as heat flow naturally occurs from hotter to colder bodies without external work.
  • Others propose that if a hot object could absorb radiation but not emit it, it would still gain heat from a cooler body, which they suggest would also constitute a violation of the second law.
  • A later reply introduces the concept of a perfect white body, claiming that it would not violate thermodynamics since it would neither emit nor absorb radiation, but only reflect it.

Areas of Agreement / Disagreement

Participants express differing views on the implications of a hot object not emitting radiation, with no consensus reached on whether such a scenario would violate the second law of thermodynamics.

Contextual Notes

Some assumptions regarding the definitions of radiation, heat transfer, and the nature of perfect bodies are not fully explored, leaving potential gaps in the discussion.

fxdung
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Why if a hot object did not emit radiation then second law of thermodynamics would be violated?
 
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fxdung said:
Why if a hot object did not emit radiation then second law of thermodynamics would be violated?
Every body in the universe emits and absorbs radiation.As far as heat flow is considered it takes place in the direction of hotter to colder body if no external work is done .The 2nd Law of Thermodynamics basically gives the direction of natural(irreversible) process which is the increase in entropy.so your hot body will radiate more than it absorbs if no work is done externally.
 
fxdung said:
Why if a hot object did not emit radiation then second law of thermodynamics would be violated?
If a hot object did not emit radiation but could nonetheless absorb radiation then it would gain heat from a cooler body that did radiate. That would be a 2nd law violation.
 
fxdung said:
Why if a hot object did not emit radiation then second law of thermodynamics would be violated?
A perfect white body does not violate thermodynamics. It would neither emit nor absorb any radiation, but simply reflect it.
 
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