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Homework Help: Brass Compression

  1. Apr 1, 2010 #1
    1. The problem statement, all variables and given/known data

    A 1.8- m long brass bar has a square cross section 1.3 cm on an edge. The bar is compressed by a force of 9.0×10^3 N applied to its ends. By how much does the bar shorten (in m)?

    2. Relevant equations

    There is an example in our book explaining how to use a variation of Young's Modulus. ΔL = FL/YA

    3. The attempt at a solution

    Change 1.3 cm into .013 m.

    (9.0x10^3 N)(1.8m) / (91 x 10^9 N/m^2)(.013^2) = .0011 m

    I squared .013 since it's the area squared.. and the 91 x 10^9 is the value for brass in the Elastic Moduli.

    Of course this is wrong, but not sure what I'm not doing quite right.
  2. jcsd
  3. Apr 1, 2010 #2
    Nevermind guys, that turned out to be the CORRECT answer.

    The online Homework program had the answer listed as .00105 m

    Since I was putting .0011 in it did not accept my answer. Go figure *sigh*
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