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Homework Help: Semi-Atwood Machine

  1. Sep 28, 2009 #1
    1. The problem statement, all variables and given/known data

    Again, I've uploaded a diagram of the problem.

    In the setup shown, m1 = 0.30kg, m2 = 0.45kg and theta = 11 degrees. Also, between the first block and the incline, coefficient of friction = 0.40. Assume the system moves so that the first block slides up the incline. (a) What is the acceleration of the system? (b) What is the tension in the string?

    2. Relevant equations

    3. The attempt at a solution

    I really have no idea how to start this. First, I suppose draw FBD for both m1 and m2. Then what should I do? I'll draw them and post them to see if I'm on the right track..

    Attached Files:

  2. jcsd
  3. Sep 29, 2009 #2
    Here are my FBDs. I'm just not sure what to do next.

    Attached Files:

  4. Sep 29, 2009 #3

    Doc Al

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    Staff: Mentor

    Once you've drawn your FBDs, use them to apply Newton's 2nd law to each mass. You'll get two force equations, which you can solve together to find the acceleration and the string tension.
  5. Sep 29, 2009 #4
    I do understand that.. I'm having trouble coming up with the correct equations. I'll attempt it again and post here and see what I'm doing wrong.

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