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Homework Help: How to prove this connection

  1. Nov 9, 2008 #1
    I have to prove in a conservation of energy question

    T-W =(mv^2)/L

    mgL(1-cosO)=(mv^2)/2

    mg=W

    T=W(3-2Cos0)

    How could I go about starting this?
     
  2. jcsd
  3. Nov 10, 2008 #2

    CompuChip

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    Science Advisor
    Homework Helper

    Assuming you can use the first three equations, use the first one to isolate T, then use the second one to get rid of the (mv^2) and finally replace the third one wherever possible. It should work out... just try it and post how far you get.
     
  4. Nov 10, 2008 #3
    I got it:

    T-W =(mv^2)/L
    mgL(1-cosO)=(mv^2)/2

    T=(mv^2)/L+W
    mv^2=2mgL(1-cosO)
    T=(2mgL(1-cosO))/L+W
    T=(2W(1-cosO))/+W
    T=2W-2WcosO+W
    T=3W-2WcosO
    T=W(3-2cosO)

    Thanks
     
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