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Homework Help: Incline plane and static friction

  1. Oct 22, 2007 #1
    1. The problem statement, all variables and given/known data

    A block sits on an inclined plane, which is slowly being raised. The block remains motionless until the angle the plane makes with the horizontal is 23°. At this angle, the block begins to slide down the plane. What is the coefficient of static friction between the plane and the block?

    2. Relevant equations

    F(static friction)= u(s) Fn
    mgsin(23)= x component
    mgcos (23)= y component

    3. The attempt at a solution

    I don't know where to even start since it doesn't give me a mass or weight...
  2. jcsd
  3. Oct 22, 2007 #2
    This angle at which the block just starts to slide is called sliding angle. What is the relation between the tangent of sliding angle and coefficient of static friction?
  4. Oct 22, 2007 #3
    coefficient of static friction=tan (x)
    oh..so the answer is tan (23)=.4244
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