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Homework Help: Question on gravitational field

  1. Jul 25, 2010 #1
    1. The problem statement, all variables and given/known data
    Considering only the gravitational fields of the Earth and the Moon, find the distance from the Earth at which a space capsule travelling between the Earth and the Moon is subject to zero gravitational force.

    Mass of the Earth = 5.98 x 1024kg
    Mass of the Moon = 7.35 x 1022kg
    Radius of Moon's orbit = 3.84 x 108m
    Radius of the Earth = 6.38 x 106m
    Radius of the Moon = 1.74 x 106m

    2. Relevant equations

    3. The attempt at a solution

    Let x be the distance between the centre of earth and the point of zero gravitational field

    Gravitational field due to Earth = Gravational field due to Moon
    GME/x2 = GMM/(R - x)2
    x = (ME/MM)1/2R/((ME/MM)1/2 +1)
    = 3.79 x 108

    But the answer provided is 3.46 x 108

    Can anyone tell me where I went wrong?
  2. jcsd
  3. Jul 25, 2010 #2

    Filip Larsen

    User Avatar
    Gold Member

    Since the symbolic result is correct you must have made an error during the actual calculation of the number.
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