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Confusion over gravity and tides

  1. Dec 9, 2008 #1
    I am having trouble rationalising the fact that the moons gravity is a fraction of the earths and is far out in space, but still manages to out pull the earths gravity albeit a tiny amount and create tides?
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  3. Dec 9, 2008 #2


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  4. Dec 9, 2008 #3


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    One thing that might help is to recall that the tides are caused only by the difference between forces. It's true that the Earth's gravitational field has much more pull on the seas than the Moon's. But, the Earth's pull on the sea is pretty much the same all over. So, the oceans all over the Earth "feel" the Earth's gravitational pull about equally; like a perfectly ballanced system. The tiny influence of the Moon is then enough to upset that ballance.
  5. Dec 9, 2008 #4
    Thanks guys, is the assumption that gravity travels in waves and if so is there evidence of reinforcement or canellation. Hence my original question should the opposing gravity waves result in the Moons being totaly cancelled out before reaching Earth.
  6. Dec 9, 2008 #5


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    The force of gravity is not carried by waves. There are gravity waves, but they have the same relationship to the pull of gravity as light has to the pull of a magnet.
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