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Featured I A perfectly stiff wheel cannot roll on a stiff floor?

  1. Dec 2, 2017 #101

    PeroK

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    It occurs to me that if a perfectly rigid wheel cannot roll, then it cannot do anything.

    The same practical arguments relating to molecular interactions etc. apply equally to its internal structure and make its existence impossible.

    As soon as we say "perfectly rigid wheel" we are in the realm of an idealised mathematical model. Any talk of atoms is absurd in this model, for many reasons.

    It's a bit like advancing practical reasons why a point particle, say, cannot move in a perfect circle.
     
  2. Dec 2, 2017 #102
    Envision: High tinsel steel ball bearing, High tinsel steel plate, no deformation of either will occur, however, apply any force to the bearing either directly (even with a simple magnet to avoid physical contact) or by tilting the metal plate (imposing gravity) and it will roll quite well. No deformation of either surface is needed. In fact, any deformation of either surface simply impedes the motion even if only by absorbing the energy required to deform the surface.
     
  3. Dec 2, 2017 #103
    Envision: High tinsel steel ball bearing, High tinsel steel plate, no deformation of either will occur, however, apply any force to the bearing either directly (even with a simple magnet to avoid physical contact) or by tilting the metal plate (imposing gravity) and it will roll quite well. No deformation of either surface is needed. In fact, any deformation of either surface simply impedes the motion even if only by absorbing the energy required to deform the surface.
     
  4. Dec 2, 2017 #104

    jbriggs444

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    It is not enough to have high tensile strength. If you want a perfectly rigid wheel with an infinitesimal contact patch, you need infinite tensile strength. That is impossible to find in nature.

    [Tinsel is the stuff you put on Christmas trees]
     
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