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General question about gravity.

  1. Apr 28, 2004 #1
    Is the strength of gravity dependant on other things besides mass such as volume or density? For instance, if our Earth had three times the diameter as it does now but contained the same amount of matter would I weigh any more or less? Or if our Earth had half the diameter as it does now would I weigh the same?

    Thank you,
  2. jcsd
  3. Apr 28, 2004 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Newton's Law of gravity

    Yes, gravitational attraction depends on distance. Your weight on the Earth's surface is related to your distance from the Earth's center according to Newton's Law of gravity:
    [tex]F = G\frac{Mm}{R^2}[/tex]
    where M = mass of Earth, m = mass of you, and R = radius of Earth (treating the earth as symmetrical ball). G is a constant.

    So if you keep the Earth's mass (M) the same, but triple its radius, your weight would be 9 times less.
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