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Homework Help: Coefficient of friction of a ramp

  1. Oct 6, 2009 #1
    1. The problem statement, all variables and given/known data

    A student has two ramps, both of which are at an angle of 30o. Ramp 1 is frictionless and ramp 2 has friction. The student also has two blocks, one for each ramp. She pushes the blocks up the ramps with the same initial velocity. The block on ramp 2 only travels a fraction f = 0.625 as far as the block on ramp 1 before coming to a stop (i.e. d2 = 0.625*d1) .

    2. Relevant equations


    3. The attempt at a solution

    I am way stuck on this!
  2. jcsd
  3. Oct 7, 2009 #2


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    Homework Helper

    Hi maladroit, welcome to PF.
    While posting any problem, state it completely as it is given in the home work.
    In the above problem what is required? Are the two blocks identical?
  4. Oct 7, 2009 #3
    That is exactly as the problem is written, the only thing I forgot to include was that we are looking for the coefficient of friction. Sorry about that!
  5. Oct 7, 2009 #4


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    Homework Helper

    In the ramp 1, the retardation is g*sinθ.
    Initial velocity is v and the final velocity is zero. So
    v^2 = 2*g*sinθ*d
    In the second case, the normal reaction is mgcosθ and frictional force = μmgcosθ.
    So the net retardation is (g*sinθ + μgcosθ)
    Now write down the expression for v^2 and solve for μ.
  6. Oct 7, 2009 #5
    Thank you so much for the help!
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