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Homework Help: The figure below shows an object on an inclined

  1. Apr 18, 2013 #1
    1. The problem statement, all variables and given/known data

    The figure below shows an object on an inclined ramp of mass 1.30 kg. The angle of the inclined surface is 25° with the horizontal. The object on the ramp is connected to a second object of mass 2.98 kg on a horizontal surface below an overhang that is formed by the inclined surface. Further, an external force of magnitude 10.73 N is exerted on the object on the ramp. We observe both objects to accelerate. Assuming that the surfaces and the pulley are frictionless, and the connecting string and the pulley are massless, what is the tension in the string connecting the two objects?


    2. Relevant equations


    3. The attempt at a solution

    1, For block 1, i dont know if my forces are correct, they seem to be wrong
    For block 2, mg and T are in different directions, how do I use ma= net force?
    Does the normal force on block 2 cancel out with the m2g so ma= Ft?

    1.3 a = 10.73N - Ft - mgsin25
    1.3a = 5.346 - Ft
    2.98a = Ft
    a = 1.249 m/s^2

    Attached Files:

  2. jcsd
  3. Apr 18, 2013 #2

    Simon Bridge

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    I cannot see the geometry of the situation from your diagram. eg. I see two blocks in the diagram, both with forces mg on them, one directly below the other, but no means to attach them. There are no pulleys in the diagram either.

    This is probably the source of mistakes ... redraw the diagram more carefully and start again.
    Draw free body diagrams for each mass.
  4. Apr 18, 2013 #3


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    You can forget/ignore mg on block 2. It's acting at 90 degrees to FT. There is no friction so for block 2...

    FT = m2 * a
    Last edited: Apr 18, 2013
  5. Apr 18, 2013 #4

    then is my calculation correct?
  6. Apr 18, 2013 #5


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    Only had a quick look but seems ok to me.
    Don't forget the question also asked for the tension.
  7. Apr 18, 2013 #6
    Ok, thanks!!
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