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Astrophysics question watch

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    I was reading an article trying to explain why Venus rotates retrograde instead of prograde as predicted by the nebular hypothesis.
    One theory was that earth's gravity pulled on a bulge but this is deemed unlikely (1) because Venus has no distinct bulge, it is rounder than earth, and (2) because tidal forces are very weak, decreasing with the cube of the distance.

    Can anyone confirm this last point as another article I read said that gravity decreases with the square of the distance.
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    Do you know what is meant by tidal forces?

    Tidal forces
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    (Original post by MC REN)
    Do you know what is meant by tidal forces?
    Tidal forces
    I have a better understanding after that thanks, but still don't know the answer to my Q.
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    (Original post by NJA)
    I have a better understanding after that thanks, but still don't know the answer to my Q.
    From the article:



    So the force goes as the cube of the distance. This is because it is a secondary effect.
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    (Original post by TableChair)
    So the force goes as the cube of the distance. This is because it is a secondary effect.
    OK, for me to understand that, what is a "secondary effect" ?
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    (Original post by NJA)
    OK, for me to understand that, what is a "secondary effect" ?
    The tidal force is more a difference between two forces. For instance say I had two point masses, the gravitational force on each from a large body would drop off as the distance squared, but the difference between the forces on each would drop off as the distance to the large body cubed (approximately).
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    (Original post by TableChair)
    . .say I had two point masses, the gravitational force on each from a large body would drop off as the distance squared, but the difference between the forces on each would drop off as the distance to the large body cubed (approximately).
    hmmm . . .why?
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    (Original post by NJA)
    I was reading an article trying to explain why Venus rotates retrograde instead of prograde as predicted by the nebular hypothesis.
    One theory was that earth's gravity pulled on a bulge but this is deemed unlikely (1) because Venus has no distinct bulge, it is rounder than earth, and (2) because tidal forces are very weak, decreasing with the cube of the distance.

    Can anyone confirm this last point as another article I read said that gravity decreases with the square of the distance.
    Gravity follows the inverse square law as far as I can remember. You got that bit right.
 
 
 
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