Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
Note also that the procedure is NOT mathematically correct if the two
bodies are "nailed to the fabric of space". In this case it's like
having two blobs of jelly (in the English sense - I can't think of
the American word) staked through their centres: they'll bulge
towards each other, yes, but not away from each other. Or perhaps it
depends on just how the bodies are nailed. I think the point is that
you get TWO tidal bulges when the bodies are in free fall,
accelerating towards each other, regardless of whether there is
circular motion, but the nailing is a red herring. Centripetal
effects are not essential, but I don't see how one can avoid the
centre of mass (Plait doesn't avoid it btw as he is taking the force
of the moon on the centre of the earth and subtracting the local
force of the moon), as the whole thing depends on the fact that the
body has the same acceleration everywhere, determined by the position
of its centre of mass, but the gravitational pull on it differs from
place to place, so the body has to deform - in both directions,
making two bulges.