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Homework Help: Young's Modulus/Breaking Point

  1. Oct 22, 2004 #1
    I've got a homework problem that starts like so:

    Assume that Young's Modulus is 1.5 x 10^10 N/m^2 for bone and that the bone will fracture if stress greater than 1.5 x 10^8 N/m^2 is imposed on it.

    If the effective diameter of the bone is 2.5cm, what is the maximum force that can be imposed on it (before breaking, I assume)

    Here's what I've done:
    A=(.0125m)2π = 4.91*10^-4 m^2
    1.5*10^8 N/m^2 = F/A
    1.5*10^8 N/m^2 = F/(4.91*10-4m^2)
    3.055*10^11 = F

    Problem is, that's a completely off-the-wall figure to get. It equates to about 68 billion pounds, and I know that bone would break well before then. I assume that the Young's Modulus provided isn't perfect, but couldn't be that far off.

    So where did I go wrong?

    Thanks in advance,


    Edit: I got it, finally. Apparently, Algebra > Me :cry:
    Last edited: Oct 22, 2004
  2. jcsd
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