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: Bone CompressionTension problem

  1. Nov 5, 2006 #1
    When subjected to a force of compression, the length of a bone (compression Young's modulus 9.4 x 109 N/m2, tensile Young's modulus 1.6 x 1010 N/m2) decreases by 3.7 x 10-5 m. When this same bone is subjected to a tensile force of the same magnitude, by how much does it stretch

    Ok after carefully looking at this problem I realized that the formula that would apply here would be

    F = Y (delta L/ L0 ) A

    Where y = young's Modulus Delta L = change in length and A = cross sectional area. But after looking at this problem I realized that there is no cross sectional area given, therefore I'm thinking that it is just a proportional problem.

    It seems like I'm making this problem a bit harder then it actually is. Perhaps I'm missing something important?

    I know that Tensile force is opposite Compression but in this case the answer would not just be the negative change in length right?

    Please help
  2. jcsd
  3. Nov 5, 2006 #2
    ya plzexplain even i did not understand
  4. Nov 5, 2006 #3
    force magnitude, initial length and cross sectional area are the same both times. differs only Y and delta L.
  5. Nov 5, 2006 #4
    ok I got it thanks :) just had to set Y1 delta L = Y2 (x) and solve for X. You see I knew I was thinking about this problem a bit too hard LOL.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook