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Homework Help: Gravitational Potential energy question

  1. Jun 14, 2010 #1
    1. The problem statement, all variables and given/known data
    a 5.00 x 10^2 kg satelilite is in circular orbit 2.00 x 10^2 km above earth's surface. calculate

    a) gravitaional potential energy which i got, which is -3.13 x 10^10 J
    b) kinetic energy of the satellite
    c) binding energy of satellite
    d) the percentage increase in launching energy required for the satellite to escape earth

    2. Relevant equations


    Eg = - GMem/re

    3. The attempt at a solution

    v = sqroot GM/r for the velocity then using the equation 1/2mv^2 to get the Ek, but i dont know how to get the radius so i can plug it into the Ek equation.
  2. jcsd
  3. Jun 15, 2010 #2


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    The earth has a radius of 6000 km.
  4. Jun 15, 2010 #3


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    Science Advisor

    How did you get the gravitational potential without knowing the radius?
    That's Schwarzschild Radius. That is not a relevant equation for this problem.
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