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Homework Help: Reaction force

  1. Jan 25, 2009 #1
    1. The problem statement, all variables and given/known data

    Is it necessary to have a normal reaction whenever 2 surfaces are in contact with each other?

    3. The attempt at a solution
    I thought the answer was "no". But my book says "yes".
    I can support my answer with an example:
    the normal force between the surface of a block and the floor of a freely falling lift under gravity is zero.

    Please help me. Does my book author takes the molecular level forces into account when he goes on to say "yes"???
  2. jcsd
  3. Jan 25, 2009 #2

    Doc Al

    User Avatar

    Staff: Mentor

    What book are you using? Does the book give an explanation or just make a statement?

    I would say that in the usual sense of the term you can have a zero normal force between surfaces in contact.
  4. Jan 25, 2009 #3
    Its called "The Pinnacle FIITJEE package for Newton's Laws". I was just going through it when I found this.
    It has just made an emphatic "YES" with no explanations whatsoever.

    Thanks a lot. I think it might just be a misprint or something.
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