Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Uniform Lamina

  1. Nov 3, 2005 #1
    Where is the centre of mass of a semicircular lamina which is uniform? I know it is somewhere along the line of symestry, but where excactly?:confused:
     
  2. jcsd
  3. Nov 3, 2005 #2

    Fermat

    User Avatar
    Homework Helper

    It only takes a few moments to work it out.
    com = 4r/3pi:smile:
     
  4. Nov 3, 2005 #3
    Can you be of more help please?
     
  5. Nov 3, 2005 #4

    Fermat

    User Avatar
    Homework Helper

    Of course. Drag your mouse over the answer in my last post.
     
  6. Nov 4, 2005 #5

    HallsofIvy

    User Avatar
    Science Advisor

    Surely, if you have a question like that, you know the basic formulas.

    The y-coordinate of the centroid of a region (center of mass assuming uniform density) is [tex]\frac{\int y dA}{\int dA}[/tex].
    [tex]\int dA[/tex] is, of course, the area of the region.


    Once, when I was teaching this, a student became fascinated by the word "lamina" (had never seen it before, apparently). As the last question on the final exam, I asked "What is 'lamina' spelled backwards?"

    Another student became furious with me because "That question doesn't make any sense!"
     
  7. Nov 8, 2005 #6
    Oh sorry. Haha. I didnt realise there was invisible ink on the paper.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook