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What is the altitude above earth's surface?

  1. Oct 22, 2007 #1
    Here's the question. I'm not sure how to apporoach it.

    A satellite has an orbital speed of 4.2 x 10 exponent 3 m/s. What is the altitude above earth's surface? (M of earth = 5.98 x 10 exponent 24 kg, radius of earth = 6.38 x 10 exponent 6 m)
     
  2. jcsd
  3. Oct 22, 2007 #2

    berkeman

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    Staff: Mentor

    Thread moved to Homework Help.

    What equations do you think apply? What do you know so far about forces in circular motion? What is the general equation for the gravitational attraction of two masses?

    You must show us your work before we can offer much in the way of tutorial help (see the "Rules" link at the top of the page).
     
  4. Oct 22, 2007 #3
    ok well, i think i should use the equation Fg = Gmm over r^2

    but i dont know how to find the other mass. and the radius of the satellite.
     
  5. Oct 22, 2007 #4

    berkeman

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    Staff: Mentor

    That's one of the two equations you need. What is the equation for uniform circular motion that relates the velocity (angular or orbital linear) to the mass, radius and central force?
     
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