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Homework Help: 1 of 3: Force of Gravity and Acceleration. Help!

  1. Sep 5, 2007 #1
    1. The problem statement, all variables and given/known data
    a) You are adrift in the solar system with no planet nearby and you are out at the same distance from the Sun as the Earth. What is the magnitude of acceleration due to the Sun's gravity you experience?

    2. Relevant equations
    Earth-Sun distance = 1.50 x 10[tex]^{11}[/tex]
    M[tex]_{sun}[/tex] = 2.00 x 10[tex]^{30}[/tex] kg
    R[tex]_{sun}[/tex] = 6.96 x 10[tex]^{8}[/tex]
    a = v[tex]^{2}[/tex]/r

    3. The attempt at a solution

    Honestly, I'm pretty lost at the moment as to how to find the magnitude of acceleration. Does it matter that they don't specify what "your" mass is? A nudge in the right direction would be wonderful - I could probably figure it out from there. I don't want someone to do the problem for me, because I'd like to be able to figure it out on my own.

    And I think that F = ma has something to do with this and centripetal acceleration, obviously, but I'm not sure how you find out what the velocity is. Help, please?
  2. jcsd
  3. Sep 5, 2007 #2


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    There's no rotation mentioned here. The law you want is Newton's law of gravitation. F=GmM/r^2. Use F=ma to go from force to acceleration.
  4. Sep 6, 2007 #3

    F = ma

    ma = (GmM)/r^2

    Is this correct?

    Andn what mass do I put in for myself?
  5. Sep 6, 2007 #4
    Yeah, that's right. Your mass is the little m, which will cancel in your equation above, so you don't need a value for it.
  6. Sep 6, 2007 #5
    Do you need a mass for yourself? There's m on the left and right...
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