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Homework Help: A block sliding up a ramp, solve for acceleration

  1. Oct 14, 2009 #1
    1. The problem statement, all variables and given/known data
    A block is sent sliding up a 50 degree ramp at an initial speed of 9m/s. The coefficient of kinetic friction between the ramp and the block is 0.51. Find the acceleration of the block.

    2. Relevant equations
    Fk = (Fn)uk

    3. The attempt at a solution
    umgsin50 = ma
    ugsin50 = a
    0.51(-9.8)sin50 = a
    a = -3.829

    Which is far from the right answer.
  2. jcsd
  3. Oct 14, 2009 #2
    gravity! Think about if the block wasn't initially moving, would you know how to calculate its downward acceleration from gravity alone? The friction portion seems to be correct though.
  4. Oct 14, 2009 #3


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    Homework Helper

    Hi acid234, welcome to PF.
    On the inclined plane, the retardation is caused by two factors. 1) Component of the weight along the inclined plane and 2) the frictional force. Find them
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