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Which force stops me falling through my chair?

  1. Sep 10, 2008 #1
    Hi all,

    I apologise if I'm missing some elementary point here, I'm not a physicist, just an interested layman.

    Anyway, here's the question. We know of four fundamental forces: electromagnetic, weak, strong, gravity, which may or may not be unified at whatever energy.

    Which of these forces is responsible for physical resistance? Which force stops me falling through my chair?


  2. jcsd
  3. Sep 10, 2008 #2

    Doc Al

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    Staff: Mentor

    The force that supports your weight and prevents you from falling through the chair is the contact force of the chair against your bottom. That force is electromagnetic.
  4. Sep 10, 2008 #3


    Staff: Mentor

    The only two fundamental forces that you really "experience" in daily life are gravity and EM.
  5. Sep 10, 2008 #4
    I think that Fermi statistics also plays an important role here. When the electrons in the chair and in your pants come close to each other they need to go to higher energy states, because the Pauli principle forbids them being in the same state. This energy is, of course, electromagnetic in nature. But without the Pauli principle, you would sink into the chair a bit.
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