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Homework Help: Accelerated Incline

  1. Nov 12, 2008 #1
    1. The problem statement, all variables and given/known data

    An inclined plane that makes an angle of 28° to the horizontal is mounted on wheels. A small block of mass m = 2 kg rests on the plane, held there by a coefficient of static friction µ = 0.66.

    The plane is accelerating to the right, as shown. What is the minimum acceleration in order that the block slides down the plane?

    Brief picture....
    https://tycho-s.phys.washington.edu/cgi/courses/shell/common/showme.pl?courses/phys121/autumn08/homework/06b/accelerated_incline_NWT/7.gif [Broken]

    2. Relevant equations

    3. The attempt at a solution

    So I've made a FBD...and pretty much stuck from there. My axis is regular, in the direction of the acceleration.
    F (x direction)=mgsin28 -sin62uFN...where U is the coefficient of static friction
    F (y direction=-mg + mgcos28 + cos62uFN.

    I believe these are right, and not sure where to go from here.
    I solved for FN and got around 7.4N...not sure how to relate this to the acceleration needed for the block to slide down. As usual, thanks for all help
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Nov 13, 2008 #2


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    Homework Helper

    Hi jromega3! :smile:

    It's simplest to calculate components along the slope

    what is the friction force needed to keep the block still …

    at what acceleration does that force equal µN? :smile:
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