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Homework Help: Satelite in EQUATORIAL orbit

  1. Dec 3, 2009 #1
    1. The problem statement, all variables and given/known data
    An earth's satelite is in equatorial orbit at 352,000 km above earth. What is the orbital velocity (m/s) of the satelite (4 sig figs)

    2. Relevant equations
    g1d1^2=g2d2^2 to find gravity at the height of the satellite

    3. The attempt at a solution
    I don't really know what an equatorial orbit is, i tried solving it as if it was a circular orbit but that didn't work. My guess was that equatorial means it goes around earth once per year, but no idea...
  2. jcsd
  3. Dec 3, 2009 #2


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    Equatorial orbit just means one above the equator.
    The equation you are looking for is Kepler's third law - it will give you the period of the orbit.
    Then from the distance you can work out the circumference and so the speed.

    hint - you are given an altitude but the orbit depends on the radius, from the centre of the earth
  4. Dec 3, 2009 #3
    so kepler's 3rd law is T1^2=R1^3
    T2^2 R2^3

    so T2 is the period, R1 is radius of earth, and R2 is radius of my orbit? what is T1 then?
  5. Dec 3, 2009 #4


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    Kepler's law is T^2 [tex]\propto[/tex] r^3

    You should be able to find an equation in your text book or on wikipedia involving G and the Earth's mass
  6. Dec 3, 2009 #5
    so my equation will be T^2[tex]
    \propto[/tex] 358370000^3? im getting a really low answer and according to my teacher it is wrong
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