Conduction between two materials

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    Conduction Materials
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Discussion Overview

The discussion revolves around the conduction of heat between two materials, specifically comparing metal and plastic at various temperatures. Participants explore how the thermal conductivity of materials affects the sensation of temperature when touched and the rate of heat transfer involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that a metal object feels colder than a plastic object at the same temperature because metal conducts heat away from the hand more effectively.
  • Another participant argues that even at the same temperature, metal will conduct heat into the hand at a greater rate due to its superior thermal conductivity.
  • A different viewpoint emphasizes that the rate of heat conduction depends on the temperature difference between the materials and the conduction rate of the poorer conductor.
  • Participants discuss the effect of brief contact time on the sensation of temperature, questioning whether both materials would feel the same if touched for a very short duration.
  • One participant mentions the diffusion equation as a governing principle of heat transfer, noting that diffusivity is a key parameter in this context.

Areas of Agreement / Disagreement

Participants express differing views on how the sensation of temperature is affected by the materials' thermal properties and the duration of contact. There is no consensus on the conditions under which both materials would feel the same when touched.

Contextual Notes

Some participants reference the complexity of heat transfer across boundaries between different media and the mathematical formulations involved, but these aspects remain unresolved in the discussion.

Who May Find This Useful

This discussion may be of interest to those studying thermodynamics, material science, or anyone curious about heat transfer principles in practical scenarios.

sgstudent
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When I have a metal object at 0 degrees and a plastic object at 0 degrees, the metal feels colder as heat is conducted away at a faster rate. The reason for that would be that the metal is a better conductor of heat so when my hand touches it, it can start vibrating more quickly than the plastic.

So does this mean that how fast heat gets conducted into another material depends on the warmer material? For example if the metal and plastic is at 60 degrees, when I touch them they should feel the same? Because now that heat is transferred to the hands, the rate of heat flow into the hand from the hotter object will be the same (since the kinetic energy of the metal and plastic particles is the same so they should have the same rate of heat transfer to the hand). Is this correct?

Thanks :smile:
 
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Nope. The metal would feel warmer and conduct heat into your hand at a greater rate.
Not only is the metal able to conduct heat into your hand better, it is also able to conduct heat within itself better too, so it also replaces the heat lost at the point of contact with your hand at a greater rate than the plastic can.
 
So does this mean that how fast heat gets conducted into another material depends on the warmer material?

as, posted already, no; It depends on the temperature difference between materials and the conduction rate of the poorer conductor.
 
Drakkith said:
Nope. The metal would feel warmer and conduct heat into your hand at a greater rate.
Not only is the metal able to conduct heat into your hand better, it is also able to conduct heat within itself better too, so it also replaces the heat lost at the point of contact with your hand at a greater rate than the plastic can.

Oh that's right! But if I were to touch it for a brief moment then they would feel the same? Or would the touch be too slow? Also what is the formula for this? Thanks
 
Last edited:
sgstudent said:
Oh that's right! But if I were to touch it for a brief moment then they would feel the same? Or would the touch be too slow?

That depends on how brief. If brief enough you wouldn't feel anything. A little longer and the metal would feel hot while the plastic probably wouldn't.

Also what is the formula for this? Thanks

Sorry, I don't know that one.
 
Heat transfer is governed by a second order differential equation called the diffusion equation, and the key parameter governing the rate of transfer is the diffusivity. Wikipedia is a good starting point for this
http://en.wikipedia.org/wiki/Heat_equation
Heat transfer across the boundary between different media is a little more complicated. I can refer you to appropriate texts if you are interested.
 

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