Heat from friction - the theory

  • Thread starter jon c
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Please can someone explain the theoretical mechanisms for how heat is created from friction in low wear situations in non technical but fully reasonable terms for explanation to bright 10 years olds? Many thanks in advance.

Is the only theory simply that the large scale physical motion of a substance transfers small scale motions 'molecular' to the particles of the other substance?

(I have a post also about efficient of methods of producing heat from friction.)

Regards
 

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  • #2
jambaugh
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Here is an analogy which might work. Imagine a sea. Heat is random motion so imagine the sea with lots of ripples and waves as "warmer" than a still, glassy smooth sea. Now imagine the wind blowing over the top. The wind can push the water in one direction but it also creates lots of waves and ripples, "heating" the surface.

Another analogy is the sound made when two objects rub together. Heat in a solid object is in one sense just sound noise, (randomized vibrations). Hot objects are noisy objects.
 
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Is the only theory simply that the large scale physical motion of a substance transfers small scale motions 'molecular' to the particles of the other substance?

Regards
Hi,

This sentence is just fine actually especially for a conceptual explanation without entering into technical and irrelevant details.
 
  • #4
sophiecentaur
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The molecules of the two friction surfaces are close enough to attract each other. They are displaced a tiny bit as they go past each other and the interaction is not 'elastic'. So there is net work done in the pulling and pushing. This work gives kinetic energy, in a random way, to the particles in each surface. (average) KE of molecules is the `temperature' of the bulk substance, by definition.
 

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