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Cutting, at the atomic/molecular level

  1. Apr 21, 2014 #1
    I know there is supposedly no such thing as a stupid question but this might make some of you reconsider if that is true.

    We assume that we can never actually touch something due to electron repulsion. How then is it possible for something to cut you?

    I know this sounds a lot like Zeno's paradox, which was solved with calculous. So I guess I'm wondering if there is a way to reconcile this.
     
  2. jcsd
  3. Apr 21, 2014 #2

    ZapperZ

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    Why is this a "philosophical" question?

    Zz.
     
  4. Apr 21, 2014 #3

    Drakkith

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    The repulsive EM force between the electrons is what does the cutting.
     
  5. Apr 21, 2014 #4
    Well I was thinking of it like Zeno's paradox which I assumed is a philosophical question but thinking about it now I realize a philosophical question, by definition, does not have an answer. So that must mean Zeno's paradox is no longer a philosophical question but a simple calculus question.
     
  6. Apr 21, 2014 #5
    Who assumes that? To add to Drakkith's post, sufficient electric repulsion is touching.
     
  7. Apr 21, 2014 #6
    Thank you Darkkith. That makes a lot of sense. So is it correct to say that an extremely sharp object, like a surgeons scalpel, simply allows for a more precisely applied EM force?
     
  8. Apr 21, 2014 #7
    ModusPwnd I guess a more precise operational definition has to be made for touching. Like you said our day to day definition of touching is sufficient EM repulsion.
     
  9. Apr 21, 2014 #8

    Drakkith

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    Yes, a sharp edge concentrates the applied force along a very thin line instead of spreading it out.
     
  10. Apr 22, 2014 #9

    sophiecentaur

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    I guess the density of the force (electric field) imbalance where the sharp edge contacts the material must relate to what we would normally call 'pressure'. The effectiveness at cutting and penetration boils down to pressure - on a macroscopic scale.
     
  11. Apr 22, 2014 #10

    ZapperZ

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    Thread has been retitled, to conform to our requirement that thread title must be descriptive of the content.

    Zz.
     
  12. Apr 22, 2014 #11

    Drakkith

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    I believe so since pressure is the applied force divided by the area it is applied to. P=F/A
     
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