Foucault's Pendulum Experiment

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.

"SPAWN OF A JEWISH CARPENTER: CINDY SMITH"
wrote:
"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?

At the equator, Earth's axis of rotation is exactly perpendicular to the
plane of oscillation. Therefore it cannot change the orientation of that
plane.

If you find it at all difficult to visualise why, use a pencil (rotation
axis) and a piece of large card (oscillation plane). poke the pencil
through the centre of the card. If the card is perpendicular to the
pencil, its orientation does not change when the pencil is rotated about
its longitudinal axis.

Does that help?

Best,
Stephen

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On 6 Sep 03 22:33:52 EDT, (SPAWN OF A JEWISH
CARPENTER: CINDY SMITH) wrote:

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?

Maybe this can help
http://www.si.edu/resource/faq/nmah/pendulum.htm

On Sun, 7 Sep 2003 12:24:31 +0100, "Les & Claire"
wrote:

Saw this re-created on an OU programme.... one of the best ever I thought.
Spectacular!
They also have one in the science musem
--
---
The two most abundant elements in the universe are Hydrogen and stupidity.
Why is the ratio of Hydrogen to Stupidity less in usenet than anywhere else in the universe?

"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?

Hint: Think about why it *does* rotate at the poles. The earth is twisting
beneath it.

Query: Before choosing your screen name, did you look up "spawn" in the
dictionary? I think you might have meant something else.

"Fleetie" wrote in message ...

Some of those old OU programmes were fascinating! Mind you, not the 70s ones
with bearded freaks in bad jumpers talking secants.

I bet if they still make programmes today, they're dumbed down rubbish
compared to what they used to be.


Martin

Careful young man! You are referring to my youth! I retain a special
affection for a nice jumper and hirsute adornment. Not least on
myself!

I remember a Foo-Ko pendulum at a multi-storey college in the 60's.
By slow gravitation every idiot "student" was drawn to the stairwell
where the suspending piano wire could be "plucked". Their attention
being brought abruptly to the almost invisible wire by carefully
placed paper "Do not touch" warning 'flags' applied at intervals
thoughout its vertical length. Rebellious youth had its limitations
way back then when everybody still saw everything in black and white.

On a more topical note: I have a theory that TV presenters are indeed
spawned. Thus breaking whatever tentative beneficial links there might
be between disadvantageous birth and positive parental contributíon to
the offspring's intelligence during upbringing. I have only to cite
"Click_Online". Q.E.D. Stop s******ing Frey!

Chris.B

"Chris.B" wrote in message
Careful young man! You are referring to my youth! I retain a special
affection for a nice jumper and hirsute adornment. Not least on
myself!

Ha ha! I just wish I could actively remember more of those good progs though. I remember
one where they immersed a metal sample in a tank of water and a kind of cartesian scanner
moved over the tank, measuring with ultrasound. Then they somehow plotted the results as a
load of lines using a plotter, photoreduced it, and guess what? The result was a hologram, with
which you could "see inside" the metal sample at different depths, see holes drilled in it,
etc.. It was wicked!


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.fleetie.demon.co.uk

"SPAWN OF A JEWISH CARPENTER: CINDY SMITH"
wrote:
I'm still unclear on exactly why the pendulum does not rotate at the
equator as well as why the pendulum rotates in the opposite direction
south of the equator.

Did you try the experiment that I suggested with pencil and card?

Best,
Stephen

--
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+ Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books +
+ (N51.162 E0.995) | http://www.astunit.com +
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