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Homework Help: Conservation of Energy & circular motion

  1. Apr 21, 2009 #1
    The problem is stated on the sheet i have attached along with my attempt to the possible solution. This is a proof and i am very bad at working with proofs. This seems to be a classical problem so i'm sure some of you guys might have seen it, please guide me!

    http://img22.imageshack.us/img22/1405/53811275.th.jpg [Broken]

    I have posted the problem with what i have tried... as you can see i was stuck, please guide me if my logic or math is wrong
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Apr 21, 2009 #2


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    Homework Helper

    Welcome to PF.

    Consider the conditions imposed.

    Total energy in the system is m*g*L

    To complete a circle then with Vt the velocity at the top of the circle about x

    m*Vt2/(L-x) = m*g

    m*Vt2 = m*g*(L-x)

    So ... at the top of that loop

    1/2*m*Vt2 + m*g*(2*(L-x)) = m*g*L

    Substituting ...

    1/2*m*g*(L-x) + m*g*(2*(L-x)) = m*g*L
  4. Apr 21, 2009 #3
    thanks a lot my friend.. you saved me a lot of hassle:D
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