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Homework Help: Reduce the volume of aluminumm by 10%

  1. Apr 6, 2007 #1
    1. The problem statement, all variables and given/known data

    At what ocean depth would the volume of an aluminum sphere be reduced by 0.10%?

    2. Relevant equations


    3. The attempt at a solution

    I know how to get pressure at differnt depths. But what I don't know is how much pressure it takes to reduce the volume of aluminum. I can't find a table for it anywhere.
  2. jcsd
  3. Apr 6, 2007 #2


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    That is a little hard to find. The number you are after is actually called a bulk modulus for aluminum. Try searching for that.
  4. Apr 6, 2007 #3


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    BTW, I'm also glad you aren't really trying to reduce it by 10%. Only 0.10%. Whew.
  5. Apr 7, 2007 #4
    thank you for pointing that out. I actually thought it was 10%. This whole I was thinking wow that has to be really deap.
  6. Apr 7, 2007 #5
    I found the bulk modulus in 2 places. I found it at wikipedia and the book. I used the books wich was 7x10^10. The books density for water is 1000. So when I take the modulus and multiply it be .001 then I take that answer and divide it by 1000 for the density and then by 9.8 for acceleration. That shoul leave me with height. It is was 7.142 Km. This answer is incorrect. To me it seems right but the homwork says it is 6.98. Why was my first answer wrong?
  7. Apr 7, 2007 #6
    have you tried using density of sea water? thas should reduce the result by about 2.5 to 3 percent.
    Last edited: Apr 7, 2007
  8. Apr 7, 2007 #7
    That must be what it is. I just used water.
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