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Homework Help: Coefficient of kinetic friction on wooden plane question

  1. Oct 19, 2011 #1
    1. The problem statement, all variables and given/known data
    This is what I was given:
    A block is placed on a rough wooden plane it is found that when the plane is tilted 30° to the horizontal, the block will slide down at a constant speed.

    2. Relevant equations
    I'm not sure which equations to use other than sinΘmg but I'm not getting the correct answer which is 0.577.

    3. The attempt at a solution
    I then tried tanΘ and got the correct answer but I'm not sure why it's correct.
    Thank you for any help provided.
    Last edited: Oct 19, 2011
  2. jcsd
  3. Oct 19, 2011 #2
    Drawing a FBD is a MUST. This must show all the forces acting on the block.
  4. Oct 19, 2011 #3
    Try a sanity check: What happens as the plane's tilt approaches 90°? Once you do that, try calculating the friction force.
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