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Homework Help: Human Bone Youngs Modulus and Load Question

  1. May 26, 2010 #1
    1. The problem statement, all variables and given/known data

    A human bone has a youngs modulus of 10^10 N m^-2. It fractures when the compressive strain exceeds 1%. What is the maximum load that can be sustained by a bone of cross sectional area 3cm^2?

    2. Relevant equations???

    F= Y*(change in length/ original length)* cross sectional area



    3. The attempt at a solution

    F= (10*10^10)* (1/100)* (3^2)

    I then get the answer 9* 10^8

    I dont understand what units I am supposed to use...and if this answer appears correct or not.

    Can anyone shed any light? Have I done this correctly?

    TIA! :)
     
  2. jcsd
  3. May 26, 2010 #2
    you cant use cm^2 your constant is in N/m^2, also you dont square it.......
     
  4. May 26, 2010 #3
    i get 30000N newtons is the unit from your actual question
    ps Y is 10^10 not 10*10^10 could be a typo??
     
  5. May 26, 2010 #4
    When I take onboard the tips you have given me, I get the same answer as you! I thought (10* 10^10) was the same as (10^10)???

    Anyway, I also received an answer of 30000.

    Is that the final answer? Do I need to do something with the results? Isnt that too big?
     
  6. May 26, 2010 #5
    not really sure what you mean, that is the answer.... units of force are Newtons. and who did you recieve an answer form... teacher???
     
  7. May 26, 2010 #6
    No I didnt receive an answer from teacher, I formulated it myself but it appears I didnt get it right!

    Thanks so much for your help, I know I am lacking the basic knnowledge for this but I am doing my best :)
     
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