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The Sun's G-Force

  1. May 17, 2003 #1
    What is the g force (anomaly) of the sun? I tried to calculate this one using Newton's equation. I did this:

    [(6.67 * 10^-11)(2 * 10^30)]/(0.7 * 10^6)

    Where F = GM/r^2 ( I think), but I got 272244898, which seems really wrong. I can't find it anywhere online and I'm trying to figure out the effect of the anomaly of a black hole on the oscillation of the fabric of spacetime due to gravitational wave propagation. I think the first step is finding the force of the sun, then multiplying that by the number of solar masses that a black hole has to find its effects on the distortion of time, etc. PLEASE let me know if you know the g force or if I am approaching this in a completely wrong manner. Thanks!
  2. jcsd
  3. May 17, 2003 #2


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    First off
    F = GMm/r²

    GM/r² gives you the acceleration due to gravity. On the surface of the Earth this comes out to about 9.8m/sec² and is called one g.

    G-force is usually considered a factor of this. (On the surface of a planet where the acceleration of gravity is 19.6m/sec² we say some one experiences 2 gs.

    Second, where did you get the value of .7 x 106 for the radius squared ? ( making the radius 836.66 meters)
  4. May 17, 2003 #3
    I got that value from some website (I knew I should have looked for a better radius). How can I figure out the g of a 10 solar mass black hole? If the sun is a certain "g" then can I multiply it by 10 to get the g of a 10 solar mass black hole?
  5. May 17, 2003 #4


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    For r u have to use the DISTANCE from the center of the sun...so u would add the radius of the sun to the distance from the sun surface to the earth's center..

    Im not sure if newtonian equations work for black holes or not..
  6. May 17, 2003 #5


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    Okay, I think I found your problem, the Sun's radius is 6.95 x 105 kilometers you have to convert this to meters first before plugging it into the formula.
  7. May 18, 2003 #6


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    The 'g' depends on where you are looking. It decreases as your distance gets farther away.
  8. May 18, 2003 #7
    There is none. "g-force" does not exist in science, it is a brand name of some PC videocards.

    Nor does Sun have any known gravitational anomaly.

    I guess you tried to calculate acceleration of gravity of Sun near Sun's surface using Newtonian formula, but forgot to convert Sun's radius into meters and to square it (gravitation obeys inverse square law). Doing arithmetic a little more accurate, you would get 272 m/s2 which is about 28 times the acceleration of gravity of Earth (near Earth surface).

    If you plug into denominator the distance between Earth and Sun, you'll get acceleration of gravity of Sun near Earth 0.0059 m/s2. Multiplying this by Earth mass 6x1024 kg you'll get weight of Earth 3.6x1022 N in gravitational field of Sun (the force with which Sun attracts Earth).

    Alternatively, you can calculate Earth gravitational field in the vicinity of Sun plugging into above formula Earth mass and Earth-Sun distance (and you'll find that gravitational field of Earth is about 0.00000018 m/s2 strong in Sun's neighborhood), and then you can calculate Sun's weight in this gravitational field of Earth: w = mg = 3.6x1022 N (which is the force with which Earth attracts Sun).

    Don't worry about that much. This is incoherent set of words (which separately do have scientific meaning however). Try to use other combinations (and permutations) of them - one day you may get lucky and have more meaningful sentence, though it may take some time (because there are about 10 terms here if not to count prepositions, and 10! is a big number).

    I think first step is to practice more in arithmetic, second - to learn some algebra, third - to learn some basic physics (concepts of acceleration, of mass, of force, etc), forth - to learn Newtonian law of gravitation, forth - to learn calculus and more physics, fifth - to learn learn tensor calculus, sixths - to learn some General Relativity. Only then IMO you will be able to at least find a right combination of such terms as black hole, gravitational wave and gravitational anomaly. (Before that - beware of 10!, it is a big number).
    Last edited by a moderator: May 18, 2003
  9. May 18, 2003 #8


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    But for a constant distance, yes, G is a multiple of the mass.
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