Energy Change in Processes: Explanations Included

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Discussion Overview

The discussion revolves around the changes in internal energy during various physical processes, specifically focusing on water freezing, a stone falling, water evaporating, and stretching a wire, all at constant temperature. Participants seek to understand whether internal energy increases, decreases, or remains constant in these scenarios.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that internal energy would increase in the processes of water evaporating and stretching a wire.
  • Another participant questions whether internal energy changes at constant temperature, proposing that it should remain unchanged.
  • There is a discussion about melting, where participants note that internal energy increases despite constant temperature, prompting questions about why this occurs.
  • It is mentioned that phase changes, such as melting and boiling, require energy input that does not change temperature but does affect internal energy.
  • Clarification is provided that while internal energy increases during melting due to heat input, the temperature remains constant during the phase change.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between temperature and internal energy, particularly regarding phase changes. There is no consensus on whether internal energy remains constant during processes like melting and boiling, as some argue it increases while others question this interpretation.

Contextual Notes

The discussion highlights the complexity of internal energy changes during phase transitions and the assumptions regarding temperature constancy. Participants do not fully resolve the implications of energy input during these processes.

Who May Find This Useful

This discussion may be of interest to students and enthusiasts of thermodynamics, particularly those exploring the concepts of internal energy and phase changes in materials.

chocofingers
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Could anybody tell whether the internal energy in the below mentioned processes is increasing , decreasing or remains the same!
And please provide explanation as well!

a) water freezing at constant temperature
b) stone falling under gravity in a vacuum
c) water evaporating at constant temperature
d) stretching a wire at constant temperature

What I believe is that it would increase in processes c & d. ?
 
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i might be wrong, but internal energy is dependent on temperature change. If temperature is constant, there should not be any change in internal energy. no?
 
yeah I too thought the same... but during melting internal energy increases ... why?? although the temperature is constant ///
 
chocofingers said:
yeah I too thought the same... but during melting internal energy increases ... why?? although the temperature is constant ///

To change the phase from solid to liquid, it takes an input of energy. This energy only causes the materiel to melt, not to increase in temperature. Once the materiel has liquified, any further energy will cause the temperature to rise again. Same thing happens when it transitions to a gas from a liquid.
 
Drakkith said:
To change the phase from solid to liquid, it takes an input of energy. This energy only causes the materiel to melt, not to increase in temperature. Once the materiel has liquified, any further energy will cause the temperature to rise again. Same thing happens when it transitions to a gas from a liquid.

So it means that during melting,boiling or any such process, internal energy remains constant ?
 
I think what drakkith is saying is, internal energy does increase in melting process as there is an input of heat energy to the substance, however temperature remains constant while melting.
 
okey thanyou, yinx & drakkith... I got it :)
 
thnxz dorebase...
 

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