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Homework Help: Help with black holes!

  1. Oct 20, 2009 #1
    1. The problem statement, all variables and given/known data

    I have a question about black holes and energy but have no idea what to do. if someone could just point me in the right direction.

    the question asks to consider a mass spiraling into a black hole, starting with energy E=0 at infinity. I have to determine E of the object when orbiting the black hole at distance r classically. I'm just stuck right now, not sure what is wrong.

    2. Relevant equations

    what im thinking;

    T(r)= 1/2 Iw^2
    U(r)= -GMm/r

    there are following questions that I can't get to until i figure this out.
  2. jcsd
  3. Oct 20, 2009 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    Your last equation is all you need. Note that this question actually has nothing to do with black holes; any normal mass will do just as well.

    - Warren
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