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Force Of gravity

  1. Dec 3, 2009 #1
    1. The problem statement, all variables and given/known data

    If the earth radius is 6.4 X 10^3 km, calculate the force of gravity on a 1.0 X 10^5 kg space station situated
    (a) earth surface
    (b) 1.28 X 10^5 km from the center of the earth
    (c) 3.84 X 10^5 from the center of the earth ( about the distance to the moon)
    (d) 1.5 X 10^8 km from the center of the earth ( about the distance of the sun)

    2. Relevant equations
    Fg = mg

    3. The attempt at a solution

    Question a

    Fg= (100000)(9.8)
    Fg= 980000

    questions b - d have been attemped but have no idea on these plz help
  2. jcsd
  3. Dec 3, 2009 #2
    Fg = mg only applies to objects less than 100 km from the Earth's surface. For b.,c., and d. you must use Fg = Gm1m2/r^2, where G is the gravitational constant, m1 and m2 are masses of Earth and satellite respectively, and r is the distance from the center of Earth to satellite.
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