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Center of mass of composite body

  1. Nov 21, 2012 #1
    1. The problem statement, all variables and given/known data

    In the image below, calculate the center of mass (x-bar,y-bar) of the composite body.

    2. Relevant equations

    I've used all of the equations for area for the shapes needed (triangle, square, circle).

    3. The attempt at a solution

    I have attached my calculations and would appreciate if someone could verify that they are correct.

    Thanks!
     

    Attached Files:

  2. jcsd
  3. Nov 21, 2012 #2

    mfb

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    x and y for the triangle look strange, and your area calculations are wrong.
     
  4. Nov 21, 2012 #3

    SteamKing

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    The table in your figure contains mostly formulas with no data.
     
  5. Nov 22, 2012 #4
    @Steamking: I've attached both the images with formulas and with the answers to the calculations to view.

    @mrb: I believe it is NOT an equilateral triangle therefore the formula should be correct. And the area calculations for the rest of the shapes I've verified to be correct as well.
     

    Attached Files:

  6. Nov 22, 2012 #5

    mfb

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    Who is mrb?
    Of course it is not equilateral, it has 1 and sqrt(5/4) as sidelengths.
    Judging from your formulas in columns F and G and rows 3 to 5, columns D and E are supposed to have the center of mass position of the geometric object. y=1.75 is certainly not the y-position of its center of mass (it is outside the whole object), and x=0.5 is wrong as well.

    Consider the square, for example: It has a height of 1 and a width of 1, so its area is 1. Your formula, however, gives 1.5. Even worse: It gives the same area for the hole, which is obviously wrong.
     
  7. Nov 22, 2012 #6
    Sorry.....mfb.

    I did notice those errors for the areas and they should be correct....now.
     
  8. Nov 23, 2012 #7

    mfb

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    That looks good now.
     
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