Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Density with calculus?

  1. Dec 1, 2005 #1
    density with calculus???

    here is the problem..
    A round wooden log with a diameter of 71 cm floats with 27% of its radius out of the water. What is the log's density?

    Yes my friend found the answer using integrals... I believe it was 919 kg/m3 roughly.... but is there possibly an easier way of finding this without using integrals of calculus because then it makes it too involved ok a question to me... and if there is not then could you help by showing me how he used integrals.. btw I took calculas last year and passed and now have credit for college... but It would be great if someone could explain how to get the answer...
  2. jcsd
  3. Dec 1, 2005 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I have a strong suspicion that your problem here is not calculus -- it sounds like you haven't worked on the problem at all... or at least haven't gotten to the point where one might want to use an integral.

    So what have you done?
    Last edited: Dec 1, 2005
  4. Dec 1, 2005 #3
  5. Nov 2, 2006 #4

    Divide by the distance from A to B by 2, add the boiling point of Iodine, and then tap the backs of your heels 3 times and say, "There's no place like home, there's no place like home" repeatedly until the answer appears.
  6. Nov 2, 2006 #5


    User Avatar
    Science Advisor
    Homework Helper

    It would be possible to find the volume of the submerged portion of the log using geometry. Think of the submerged cross section of the log as a circle with a wedge removed, and a triangle filling in for the missing wedge.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook