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Homework Help: Weight Away from Earth's Surface [CONCEPT-NO MATH]

  1. Dec 2, 2012 #1
    1. The problem statement, all variables and given/known data

    When calculating weights away from Earth's surface, for example:

    At 6.38x10^3 km away from Earth's surface a spacecrafts weight is d=rE+rE or 2rE
    Then F=(1/4)(SpaceCraftWeight)

    What I don't understand is why the distance is rE+rE?

    Or when 1.28x10^4 km away
    d=rE+2rE or 3rE ?

    I'm also assuming since F=mAmB/d^2
    That's why F= (1/(x^2)(W) ?
     
  2. jcsd
  3. Dec 2, 2012 #2

    Dick

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    Science Advisor
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    Because the d in F=mAmB/d^2 is the distance from the center of the earth. Not the distance to the earth's surface.
     
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