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Homework Help: Strength to Weight & Modulus to Weight

  1. Sep 6, 2012 #1
    1. The problem statement, all variables and given/known data
    σ=230MPa (tensile strength)
    E=15GPa (modulus)
    ρ=1.85 g/cm^3 (density)

    2. Relevant equations

    Strength/Weight = σ/ρ
    Modulus/Weight = E/ρ

    3. The attempt at a solution

    Strength/Weight = σ/ρ = 230x106 N/m2 / 1850 kg/m2
    = 124324.32 (Units?) ___Shouldn't this be unit less?

    Modulus/Weight = E/ρ = 1.5x10 10 N/m2 / 1850 kg/m2
    = 8108108.108 (Units?) ___Shouldn't this be unit less?

    ____Any help is appreciated, thank you__
  2. jcsd
  3. Sep 7, 2012 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Units are Nm/kg using mass density. Or if you use weight density,
    units are length units (meters or feet or inches, etc)
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