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Homework Help: Force Problem of normal force of the table

  1. Feb 21, 2010 #1
    1. The problem statement, all variables and given/known data
    A hand presses down on a book. Is the normal force of the table on the book larger than, smaller than, or equal to mg? (m is the book mass)


    2. Relevant equations
    F+mg


    3. The attempt at a solution
    I want to say the normal force is equal to mg. Am i correct?
     
  2. jcsd
  3. Feb 21, 2010 #2
    Wikipedia of Newton's 3rd Law:

    Whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction.

    The downward force of the book is F(weight) + F(applied by hand).
    Book acting on table.

    Now the table acting on book has the same magnitude of force but opposite direction (N3rd law). Force(normal).

    Hope that helps.
     
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