Does increasing the temperature of an object increase it's mass?

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Discussion Overview

The discussion revolves around the relationship between temperature, energy, and mass as described by Einstein's equation E=mc². Participants explore whether increasing the temperature of an object results in an increase in its mass, considering both thermal energy and potential energy in compressed states.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that heating an object increases its energy and, consequently, its mass, referencing E=mc².
  • Another participant agrees, stating that the measured mass would indeed increase when an object is heated.
  • A different perspective is introduced, noting that E=mc² applies to objects at rest, while objects in motion require a different equation, E²=m²c⁴+p²c².
  • One participant mentions that the kinetic energy of vibrating atoms contributes to the mass of the heated object, although they express uncertainty about whether this effect has been measured.
  • A question is raised about whether a compressed steel spring would be heavier than an uncompressed one due to stored energy, which is affirmed by another participant.

Areas of Agreement / Disagreement

Participants generally agree that heating an object increases its mass due to increased energy. However, there is a lack of consensus on the applicability of E=mc² in different contexts, particularly regarding objects in motion and the measurement of energy effects.

Contextual Notes

Some assumptions regarding the definitions of mass and energy may not be fully articulated. The discussion does not resolve whether the effects of temperature on mass have been empirically measured.

mcafej
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Ok, so I was just thinking about einsteins famous equation E=mc^2, and I was just wondering, if I were to take, say a rock or piece of metal. If I were to weigh it, and get it's mass, I could compute how much energy it contains. However, if I were to add heat to the rock or piece of metal by putting it into a fire to just heat it up, wouldn't the amount of energy that the rock or metal contains be higher, and so wouldn't the mass be higher (since the speed of light is constant, the only thing that can increase when the energy increases is mass, right?)? Anyways, maybe I'm missing an obvious point, but I was just curious about this, so any clarification would be great.
 
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You are absolutely correct. The measured mass would increase if you heat an object up.
 
Just remember that the equation E=mc^2 only applies to objects at rest. Objects in motion use the equation E^2=m^2c^4+p^2c^2.
 
mcafej said:
Ok, so I was just thinking about einsteins famous equation E=mc^2, and I was just wondering, if I were to take, say a rock or piece of metal. [..] if I were to add heat to the rock or piece of metal [..], wouldn't the amount of energy that the rock or metal contains be higher, and so wouldn't the mass be higher [..]? [..] any clarification would be great.

Yes that is correct; the kinetic energy of the vibrating atoms in that object adds to its mass. (I don't know if it has ever been possible to measure this effect.)

See also the conclusion of the related famous paper:
http://www.fourmilab.ch/etexts/einstein/E_mc2/www/

and a discussion of temperature:
https://en.wikipedia.org/wiki/Thermodynamic_temperature
 
Does this also mean that a steel spring would be measured heavier in a compressed state than in a non-compressed state as it has stored energy?
 
JustinRyan said:
Does this also mean that a steel spring would be measured heavier in a compressed state than in a non-compressed state as it has stored energy?

Yep!
 

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