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Masses on incline plane and pulley.

  1. Nov 5, 2009 #1
    1. The problem statement, all variables and given/known data

    A suspended 2.87 kg mass is moving up, a 1.5 kg mass slides down the ramp, a suspended 8.4 kg mass on the left is moving down. There is friction between the block and the ramp. The acceleration of gravity is 9.8 m/s2 . The pulleys are massless and frictionless.

    Find the acceleration of the 3 block system.
    Here is a diagram

    http://img8.yfrog.com/i/capturexki.jpg/ [Broken]


    2. Relevant equations

    F=ma
    Friction=μN
    F parallel: mgsinφ
    F perpendicular: mgcosineφ

    3. The attempt at a solution

    Sumation equation I set up (mass 1= 8.4kg, mass 2=1.5kg, mass 3=2.87kg mt=total mass)

    m1g-m2g(sinφ)-friction-m3g=mtg

    after the numbers are plugged in:

    (8.4)(9.8)-(1.5)(9.8)sin36-(0.14)(1.5)(9.8)cos36-2.87(9.8)=12.77a

    acceleration would equal=3.43 m/s2

    is this correct?
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Nov 6, 2009 #2
    i think your attempt is exactly what the question required
     
  4. Nov 6, 2009 #3
    I figured it out....

    I was forgetting to add the parallel force to the driving force.

    All is well now, thanks!
     
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