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Homework Help: Universal gravitation + orbits question

  1. Jun 7, 2009 #1
    1. The problem statement, all variables and given/known data
    A 450kg satellite is to be placed at an altitude of 2.45 x 10^6m above the earth surface. Calculate the period the satellite will have when orbiting at that altitude.

    2. Relevant equations

    m2g = Gm1m2/R^2 = m2v^2 = m2(4pie)^2 R /T^2 = m2 2pie v/T

    Ac=4pie ^2 R / T^2

    3. The attempt at a solution

    Alt= r- rp
    2.45x10^6m= r -6.37x10^6m
    8.82x10^6m = r

    I dont no what equation to use next
  2. jcsd
  3. Jun 7, 2009 #2


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    Homework Helper

    This is wrong it should be [itex]Gm_1m_2/R^2 = m_2v^2/r[/itex]

    Is also wrong I am not sure what you did here. You're also making one big equality chain which does not hold.

    Start with [itex]Gm_1m_2/r^2 = m_2v^2/r[/itex]. Do you know a formula that relates v to T for a circular orbit?
  4. Jun 7, 2009 #3
    there are several aproches to this problem. If it is a circuler or bit you could use use

    If it is not a circuler orbit you could use,

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