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Simplicity of the equation F=mg

  1. Nov 29, 2003 #1
    ok this may seem stupid to the experienced but it has bothered me for a while.
    the Equation F=mg
    is it not true that the more mass u have the greater the graviety u have?
    and if this is true why then when the equation is rearranged
    F/m=g therefore the greater mass you have the less Graviety u have?!
    C'mon people the sky is falling the sky is falling

  2. jcsd
  3. Nov 29, 2003 #2
    No, F/m=g doesn't say more mass->less gravity, it says given the force on a mass in a gravitational field and the amount of mass, there is so much acceleration. Given:
    then it should be obvious that:
    The problem in your reasoning is that you make the assumption that the force is constant as the mass increases, and this leads you to the contradictary conclusion. As shown above, the force varies with the mass, so that the answer will always be the same in a given gravitational field where the test mass is small enough not to cause any consequential movement in the tested mass (Earth).
    However, if your assumption was right, and the force on a mass was constant and independent of the amount of mass, then g would vary inversly with the size of the mass, which means that greater masses would fall slower. But they don't, so it's not.
    Last edited: Nov 29, 2003
  4. Nov 30, 2003 #3
    thanks for clearing that up that makes logical sense and you have solved an ongoing saga for me
    I guess the sky isnt falling[b(]
    it was like i was the first one out the boat on D-Day
    i got Binked
  5. Nov 30, 2003 #4
    I don't know what 'binked' means, and for future reference, something like this should be in the general physics forum.
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