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Homework Help: Center Mass of Solids

  1. Mar 8, 2008 #1
    1. The problem statement, all variables and given/known data
    What are (a) the x coordinate and (b) the y coordinate of the center of mass for the uniform plate shown in Fig. if L = 5.0 cm?

    http://edugen.wiley.com/edugen/courses/crs1650/art/qb/qu/c09/fig09_38.gif


    2. Relevant equations



    3. The attempt at a solution

    So I think I should set this up as four different rectangles with a center particle mass. So this leads to Total = 110cm, xcom = ((20(10))+(30(-5))+(20(5))+(40(5))/110

    Is this correct?
     
  2. jcsd
  3. Mar 9, 2008 #2
    You must consider the plates as rectangular lamina and first calculate their individual moment of inertia using ML^2/12.
     
  4. Mar 9, 2008 #3

    tiny-tim

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    Hi Ankh! :smile:

    First - common-sense - it's much easier if you use L throughout your calculations, and only put L = 5 right at the end - that way you're much less likely to make a mistake! :smile:

    110 is correct.

    hmm … you think I was kidding about mistakes? … try L^2 instead of L! :smile:
     
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