Cindy, it's because (I think) that the equator is too far from the earth's
axis to show rotation. In other words, there is no "earth" that is "under" a
pendulum at the equator. The surface of the earth is so far from the axis
that this particular "trick" -- and it is really a kind of trick -- only
works perfectly at the poles. It works somewhat in the latitudes that
Foucault lived in. If you are suspended above a basketball and you look down
on the top of the ball, and someone turns the ball on its vertical axis, you
will see the writing on the ball move in a circle beneath you. If you are
holding the basketball at arms length in front of you, and you turn the ball
360 degrees on its vertical axis, all you see is the lateral movement.
There's no circle visible to you at all.
"SPAWN OF A JEWISH CARPENTER: CINDY SMITH" wrote in
message ...
In article , "Bonnie Granat"
writes:
What I still don't understand is why, if the pendulum is attached to the
building, it doesn't just move along with the building!
Do you know, Cindy? Funny meeting you here!
It's a small Dyson Sphere, after all :-).
Alas, I haven't the faintest idea. I'm hoping some astronomer or
astronomy major will enlighten us.
--
___________________________
Bonnie Granat
GRANAT EDITORIAL SERVICES
http://www.editors-writers.info
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"SPAWN OF A JEWISH CARPENTER: CINDY SMITH"
wrote in
message ...
I'm reading an introductory book on astronomy called _Discovering
Astronomy_ by William H. Jeffrys and R. Robert Robbins. On page 7 is
a description of the pendulum experiment by Foucault in 1851 designed
to prove that the earth rotates on its axis. Theoretically, the
pendulum should rotate opposite to the Earth's rotation. Question 9
asks: "Why doesn't the plane of oscillation of the pendulum rotate at
the equator?" I don't know the answer. Can anyone tell me why?
Thanks.
--
Cindy Smith Unless the LORD build the house,
they labor in vain who build.
Unless the LORD guard the city,
in vain does the guard keep watch.
Me transmitte sursum, -- Psalm 127:1
Caledoni! All your base are belong to us.
A Real Live Catholic You are on the way to destruction.
in Georgia! What you say.
- - Go against the flow! You have no chance to survive make your
time.
--
Cindy Smith Unless the LORD build the house,
they labor in vain who build.
Unless the LORD guard the city,
in vain does the guard keep watch.
Me transmitte sursum, -- Psalm 127:1
Caledoni! All your base are belong to us.
A Real Live Catholic You are on the way to destruction.
in Georgia! What you say.
- - Go against the flow! You have no chance to survive make your
time.