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Posted by Josh L on August 17, 2008, 10:52 pm
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>The moon's mass is only about 1/80 of the earth's mass, and the centre
>of the moon is about 60 times further away from the earth's surface than
>the centre of the earth. So the earth's gravity, at its surface, is
>about 80 x 60 x 60 or nearly 300,000 times stronger than the moon's. I
>don't think a variation of about three parts per million in
>gravitational pull is going to make a measurable difference to athletic
>performance.
>
>On the other hand, there are variations much greater than that from
>place to place on the earth's surface, mainly due to altitude. A place
>that's 2 km above sea level is about 3e-4 earth-radii further from the
>earth's centre than a place at sea level, so the pull of gravity is
>about 6e-4 g less than at sea level. Thet's 300 times greater than the
>effect of the moon. Could that have an appreciable effect on athletic
>performances? Maybe.
>
> dow
Yes. After I posted my question I realized that I'd left out an
important part which is that any trend after the 1968 Olympics to
recognize that performing at altitude may have influenced the outcomes
of events is a trend that was taking into account both wind resistance
and gravity. Both are reduced at altitude, as is the amount of
available air for endurance event participants to breathe.
So, I was accustomed to thinking of the outfall of the '68 Olympics as
an air resistance thing, but I guess it would also be a recognition of
gravitational efffect upon performance?
I've been taught most of my life that the tides are, for the most
part, a result of the interaction of the moon with the Earth, so even
granting your equations, the effect of the Earth-moon interaction at
sea level seems to be palpable for bodies of water, and perhaps also
palpable for elite athletic competition. Now, it may not be a simple
matter of the Moon's pull so much as that plus some aspects of the
Earth's rotation and orbit that are harder to understand?
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