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Homework Help: A gravatational homework question

  1. Aug 26, 2010 #1
    1. The problem statement, all variables and given/known data
    If an object is near the surface of the earth, the variation of its weight with distance from the center of the earth can often be neglected. The accelertaion due to gravity at sea level is 9.81 m/s^2. The radius of the earth is 6370 km. The weight of an object at sea level is mg, where m is its mass. At what height above the surface of the earth does the weight of the object decrease to .99mg?

    2. Relevant equations
    I used .99mg= (Gm(me)/(6370 + x)^2) ....... where G= 6.67 x 10^-11 and me= mass of the earth
    3. The attempt at a solution

    I used the formula above and solved for x getting an answer around 1000km, there is no way for me to check my solution.... Any hints?
  2. jcsd
  3. Aug 26, 2010 #2


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    Homework Helper

    Can you show exactly how you got 'x'? Because x=1000km is a bit odd.
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