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Homework Help: Direction of the force on the ramp due to the sliding block

  1. Jan 31, 2009 #1
    How do you find the direction of force on a ramp due to a sliding block

    I thought it would be in the direction of theta on the triangle but that wasnt correct. Thank you so much for your help!
  2. jcsd
  3. Jan 31, 2009 #2
    If there is any friction, the answer depends on the direction
    in which the block is sliding.
    If no friction, then normal to the plane by definition.
  4. Jan 31, 2009 #3
    there is a coefficient of kinetic friction = 0.20

    and i had thought that the frictional force for the ramp would be in the direction that the block is sliding and the frictional force on the block would be in the other way but that doesnt seem to be the case
  5. Jan 31, 2009 #4


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    Homework Helper

    Remember friction resists motion, so it will be against the direction that it is moving.
  6. Jan 31, 2009 #5
    This applies to the friction force on the block.
    The question refers to the force exerted by the block on the ramp.
  7. Jan 31, 2009 #6
    so I tried the answer of the direction opposint the direction of friction and that was not correct, i am not sure as to what i should do to try and figure this out
  8. Jan 31, 2009 #7
    A highly relevant piece of information!
    If not specified you also have to make the assumption that the
    block is sliding down the slope.
    Given "Friction force" = 0.2 *"Normal reaction" you can easily deduce
    the angle that the resultant force makes with the normal to the plane.
  9. Jan 31, 2009 #8
    I finally got the answer and it was perpendicular to the block (the normal force) and straight down (gravity) ! thank you so much for the help!
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