1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Find the dimensions of surface tension

  1. Sep 9, 2011 #1
    I would really appreciate some help with this!

    physics.jpg


    h= (L)
    r=(L)
    p=(ML-3)
    g=(LT-2)

    I just don't know what to do with the directly proportional sign. Should I isolate the surface tension before or after adding the constant?
     
  2. jcsd
  3. Sep 9, 2011 #2
    From:

    http://www.wikihow.com/Determine-Whether-Two-Variables-Are-Directly-Proportional

    Which is from:

    http://www.google.com/webhp?hl=en&t..._gc.r_pw.&fp=1fa7c254c97e187f&biw=800&bih=417


    "Understand what the phrase directly proportional means. A very common misconception is that two variables are directly proportional if one increases as the other increases. Two variables are said to be directly proportional if, and only if, their ratio is a constant for all values of each variable. Thus when one variable is divided by the other, the answer is always a constant. "

    So in the formula for surface tension I think that the proportional sign can be replaced with an equals sign when the formula is multiplied by a dimensionless constant?

    See also:

    http://en.wikipedia.org/wiki/Surface_tension#Two_definitions
     
  4. Sep 10, 2011 #3

    ehild

    User Avatar
    Homework Helper
    Gold Member

    The directly proportional sign means a multiplicative constant K which is dimensionless. So

    [itex] h=K \frac{\gamma}{r \rho g}[/itex]

    ehild
     
  5. Sep 10, 2011 #4
    So from there I can isolate surface tension and find its dimensions?

    surface tension = (L)(L)(ML-3)(LT-2) / k

    =M/kT2

    Now how do I find the SI units with a constant in there?
     
  6. Sep 10, 2011 #5

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    As ehild said, that constant is dimensionless so you can just ignore it.
     
  7. Sep 10, 2011 #6
    Oh ok, so the SI units would be kg/s2 ?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Find the dimensions of surface tension
  1. Dimensions of tension (Replies: 1)

  2. Surface tension (Replies: 17)

Loading...