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Homework Help: Acceleration and Tension of two masses on an inclined plane with friction.

  1. Feb 25, 2009 #1
    1. The problem statement, all variables and given/known data
    In the attachment there is a drawing of the situation.
    Mass one = 4kg and Mass two = 5kg
    The coefficient of friction between mass one and the inclined plane = 0.24
    Find the magnitude of the acceleration of the masses and the tension in the cord.



    2. Relevant equations
    Fk= μkFnormal
    Fnetx=Mg*Sinϑ-Fk=Ma
    Fnormal=Mg*Cosϑ

    Fnetx=Fk+Mg*Sinϑ-T=Ma ???

    3. The attempt at a solution

    a=(Sinϑ-μkCosϑ)g.... a=9.8(Sin30-0.24*Cos30)=2.86m/s2
    t=MgSinϑ-MgCosϑ*μk-Ma... t=33.9481-8.1476-14.3=11.5N


    I'm not sure if the equation I ended up with for acceleration is correct and I am pretty sure that my equation for tension is completely wrong.

    The book is giving me the answers a=2.4m/s/s and t=37N
     

    Attached Files:

  2. jcsd
  3. Feb 27, 2009 #2
    How can this be?

    What you're doing here is calculating an acceleration of a system that has a gravity towards sky. And using the acceleration from that to determine the tension of a completely different system.

    Hint: Your completely ignoring the hanging mass. You can use it to your advantage.
     
    Last edited: Feb 27, 2009
  4. Oct 4, 2009 #3
    Awesome this helped me a lot. GOD bless you all.
     
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