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Homework Help: Co-efficient of Static Friction Question

  1. Jun 14, 2008 #1
    1. The problem statement, all variables and given/known data
    If the coefficient of static friction for a 5.0 kg rubber block on a floor is 0.72, how much force is needed to start it sliding?

    Co-efficient of Static Friction=0.72

    2. Relevant equations
    coefficient of static friction = Friction Force/Surface Normal Force (equal to the weight of the object)

    3. The attempt at a solution


    Therefore, an applied force of at least 35 Newtons is needed to overcome the Friction Force and start the object moving. But the answer in the book gave me 106 Newtons. I don't know how that was arrived at...but strangely enough 35 * 3 = 106.

    Thanks in advance for clearing up the matter for me.
  2. jcsd
  3. Jun 14, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Sounds like you are correct and the book is wrong. (I assume the force is meant to be applied horizontally.)
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