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Number of Nails in Picture?

  1. Sep 18, 2013 #1
    How many nails are in the picture? How did you arrive at this solution?

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  2. jcsd
  3. Sep 18, 2013 #2


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    I guessed
  4. Sep 18, 2013 #3
    Excellent guess. :)
  5. Sep 18, 2013 #4
    amount of nails < infinity
  6. Sep 18, 2013 #5


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    Staff: Mentor

    Including expected, but not visible nails, between 1 000 and 100 000.
    The remaining uncertainty can be reduced by a [insert your favorite useless education here] student, ...
    ...weighting them (and a few individual nails). You don't want to wait until he counted them, right?
  7. Sep 18, 2013 #6

    D H

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    That looks like about 5 pounds of 2" common nails, so 800-900 nails, depending on the manufacturer.
  8. Oct 1, 2013 #7
    answer is zero nails. since op was asking for human nails. end thread/
  9. Oct 1, 2013 #8
    best bet is 1600. Please count it!
  10. Oct 1, 2013 #9

    D H

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    Don't you just hate these post and run kind of brain teasers?

    It's been two weeks since the person who posted the question last came back to the site.
  11. Oct 2, 2013 #10
    I DON'T KNOW. However I will try a stupid approximation technique:

    Let N be the number of nails ,
    V be the average volume of the nail bulk, and u be the average volume of a single nail (at different orientations). Let l be the length of a single nail. Exclude the empty spaces between the nails!

    Identify the average shape of the nail bulk. Find u with respect to l (I.e. u = f(l) ). Find V with respect to l (I.e. V = g(l) ).

    Now Nu = V, so N = (V/u) = g(l)/f(l)
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