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Homework Help: Gravitational field strength formula

  1. May 9, 2005 #1
    Q: "The Earths radius is 6700km. Show that the magnitude of the gravitational field strength at a height of 350km above the Earth's surface is about 9 N/kg"

    I got the mass of the Earth which is 5.98E 24
    G the constant = 6.67E -11

    Formula : g= GM/r² , i cant seem to get 9, am I supposed to use the 350km??
  2. jcsd
  3. May 9, 2005 #2
    Yeah, at a distance R away, the gravitational force is

    [tex] mg = \frac{GMm}{r^2} [/tex]

    Your distance R is 350km above the earth's surface .
  4. Sep 22, 2011 #3
    Make sure your 350km is in metres!
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