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Homework Help: Weight of a man orbiting this given planet

  1. Nov 6, 2011 #1
    1. The problem statement, all variables and given/known data

    The mass of one planet in a distant galaxy is 0.58 that of the Earth's mass , and its radius is 0.57 that of the Earth's radius.

    What is Fnew, the factor by which the man's weight is reduced if he were orbiting the planet at a distance of 3.5 Earth radii above the planet's surface? i.e., Weight(3.5 Earth radii above planet's surface) = Weight(at planet's surface)/Fnew

    I know that the man is 82kg and weighs 1436.022N on the surface of the planet.

    2. Relevant equations

    F= (M x m)/R^2

    3. The attempt at a solution

    I've tried doing .58/(.57+3.5)^2 times 82 and a few other things but I'm just not really sure how to solve this problem and it's been frustrating me for a few hours.

    Thanks for the help!
  2. jcsd
  3. Nov 6, 2011 #2
    I think you are missing a G in that equation up there?

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

    What is the mass of the planet, and it's radius? You should be able to solve for his weight floating above the planet with this information.
    Last edited: Nov 6, 2011
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