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Homework Help: Trouble with this equation

  1. Sep 9, 2004 #1
    [tex]P= \frac{2 {\p} G}{3}p^2r^2[\tex]

    i need to find r =

    just having trouble where to start!

    I have tried a few times.

    just a bit stuck!

    Any help would great !

    Thanks in advance
     
  2. jcsd
  3. Sep 9, 2004 #2
    OK lets try again!

    [tex]P= \frac{2 {\p} G}{3}p^2r^2[/tex]

    i need to find r =

    just having trouble where to start!

    I have tried a few times.

    just a bit stuck!

    Any help would great !

    Thanks in advance
     
  4. Sep 9, 2004 #3

    jcsd

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    Science Advisor
    Gold Member

    Divide both sides by p^2 2G/3
     
  5. Sep 10, 2004 #4
    I have divided by this but i don't seem to get the radius i am given

    I end up with R = SQUARE ROOT P2G/3

    am i on the track or have mixed up the equation

    j
     
  6. Sep 12, 2004 #5
    "I end up with R = SQUARE ROOT P2G/3"
    -----

    You made a mistake while dividing. You should end up with
    [tex]r^2 = \frac {3P} {2Gp^2} [/tex]
     
  7. Sep 12, 2004 #6
    Yes i have managed to rearrange to and i have that part. The next part of the question ask
    to rearrange another equation that is similar to the original equation given but instead it is 2pieG/3*P^2*R^2 and then find R

    I have managed to get R = Sqrt3P/2pieGP

    any help would be great in pointing me in the right direction

    I am not getting the right figure for R so i must messing up this equation
    2pieG/3*P^2*R^2



    thanks :grumpy:
     
    Last edited: Sep 12, 2004
  8. Sep 15, 2004 #7
    I figure it out

    My brain must have gone walk abouts for the past week!

    j
     
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