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Homework Help: Finding the acceleration of a pulley system

  1. Oct 2, 2012 #1
    1. A pulley system consists of Mass A (400g) on a wooden ramp being pulled by Mass B (300g) which is suspended in the air. The board is placed on a table at an angle of 12 degrees. The following values are for the system: Hypotenuse(Length of board): 50cm, Height from table to board (a from pythagoren thereom): 15cm and table length (b from PT): 48cm and the height of the table is 37 cm. Calculate the acceleration of the system

    2. I have a derived equation from a previous question:
    [itex]\frac{acceleration of system= (mass of A)(gravity)-mass of b(sin [degree])}{mass of a + mass of b}[/itex]

    3. I have a good idea what to do, but just because the equation I have does not account for friction and this one does so I am not sure what to do for it. How would I incorportate friction? Thanks, I am getting frustrated
    Last edited: Oct 2, 2012
  2. jcsd
  3. Oct 2, 2012 #2


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    It is a very bad idea to use equations obtained from one problem and apply them to another. Especially when the equation is wrong to begin with. Instead, use free body diagrams for each mass to identify all forces acting, then use Newton's laws. Your calculation for the height of the board above the tabletop is also not correct. I dont see friction noted anywhere.
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