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Friction and tensions with two blocks on a string on an incline

  1. Jan 18, 2010 #1
    1. The problem statement, all variables and given/known data
    Two blocks are connected by a string over a frictionless, massless pulley such that one is resting on an inclined plane and the other is hanging over the top edge of the plane. the hanging block has a mass of 16 kg and the one on the plane has a mass of 8 kg. the coefficient of kinetic friction between the block and the inclined plane is 0.23. the blocks are released from rest.
    Edit: The incline is at an angle of 37 degrees.

    a. what is the acceleration of the blocks?
    b. what is the tension in the string connecting the blocks?

    2. Relevant equations
    Ffr=Coefficient x Fn
    A= Fnet / Mass

    3. The attempt at a solution
    I solved for the Fgx and the Fgy using cos and sine. I got Fgx= 47.18 N, and for Fgy= 62.6 N. I solved for Force of friction using equations above and got 14.4 N. Also I found the Fg for the 16 kg block to be 156.8. So I found Fnet of the whole system = 95.22. Divided by mass of 24 gives an acceleration of 4 m/s2 (I think ?)

    For tension, so far I have figured the tension of the string of just the 16 kg block to be 92.8 N ? Not sure where to go now..
    Last edited: Jan 18, 2010
  2. jcsd
  3. Jan 18, 2010 #2


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    It seems that you're doing it right, but what's the angle of inclination of the plane? You seem to have forgotten to tell us this.
  4. Jan 18, 2010 #3
    Oops, sorry, the incline is at an angle of 37 degrees.
  5. Jan 18, 2010 #4


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    Then I think your calculations are fine.
  6. Jan 18, 2010 #5
    Okay thank you! But is my tension right? I found tension for the string above the hanging block to be 92.8 N but I'm confused as to if I have to add anything to this? or the tension is the same throughout the string??
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