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

Homework Help: AP PHYSICS ~ FLUIDS ~ A cube of osmium with a volume of

  1. Dec 5, 2012 #1
    A cube of osmium with a volume of 166 cm³ is placed in fresh water. The cube's apparent weight is 35.0 N. What is the density of osmium?

    This is what I did:

    I converted force to mass by : 35 N / 9.8 = 3.57 kg

    then changed the 166 cm³ to m³ which is : .000166 m³

    After that i divided the mass and the volume: (3.57 kg)/(.000166 m³)

    And so I got the density as 21506 kg/m³

  2. jcsd
  3. Dec 5, 2012 #2


    User Avatar
    Science Advisor
    Homework Helper

    What did you do with the Archimedes principle/force ?
  4. Dec 6, 2012 #3
    Your conversion from cm^3 to m^3 was off, it's actually 1.66m^3, you move it two decimal places to the left.
  5. Dec 6, 2012 #4


    User Avatar
    Science Advisor
    Homework Helper

    That is correct, and iilego's post #3 is wrong.

    The question says "the cube was placed in fresh water". You haven't used that information anywhere. What difference does it make if the cube is in water or in air?
  6. Dec 6, 2012 #5
    cm equals .01 meters, which is two decimal places to the left, am I wrong? I never mentioned anything about the answer, just that his conversion was off on the volume.
  7. Dec 7, 2012 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    If 1 cm = 0.01 m, then (1 cm)^3 = 1 cm^3 = (0.01 m)^3 = 10^(-6) m^3

    1m^3 is rather a large volume
  8. Dec 7, 2012 #7
    never mind, I was wrong, the conversion was right, sorry :(
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook