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Re: [Phys-l] gravitational force



People TODAY believe this stuff -- the Flat Earth Society still exists
(headquarters in California).

Ask your students (or anyone) how they know the Earth is round, and you'll
get some interesting answers. Without looking at photographs or flying in
a plane, it's difficult (for most people) to PROVE the Earth is round...

Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu> writes:
Speaking of myths, Robert Crease discusses the issue of what he calls
"Physics Legends" in his November column in Physics World
http://physicsweb.org/articles/world/19/11/3/1

In my classes, after showing how one gets the mass of the earth in terms
of g, G and R, I often ask how long we've known these quantities.
Most semesters students can relate g to Galileo's time ( and of course G
to Cavendish since we just discussed it) but the surprising thing is
that most students think that
the radius of the Earth is very recent knowledge (most think it is less
than 500 years old) and invariably ask how come people believed the
earth was flat if Eratosthenes
got it right ( or close enough) over 2000 years ago. From what I was
able to gather, the belief that the earth is flat is mostly a legend
invented in the 19th century as a put down of the medieval people
(Washington Irving is often mentioned as the main culprit).

Karim Diff

jbellina wrote:
I stand corrected...another physics textbook myth bites the dust.

joe

Joseph J. Bellina, Jr. Ph.D.
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556

On Nov 1, 2006, at 2:27 AM, Bernard Cleyet wrote:


For about 20 years the intermediate and advanced labs. at UCSC were
largely based on the famous basic experiments, e.g. oil drop, Fizeau -
Foucault speed of light, Cavendish, etc. We kept a file of the
original
papers and the students were expected to read them. They are 40 miles
away, so I suggest one take advantage of JB's cross posting and check
for ones self:


http://www.journals.royalsoc.ac.uk/(dr5ece551054aw45zsveyx55)/app/
home/main.asp?referrer=default
<http://www.journals.royalsoc.ac.uk/%28dr5ece551054aw45zsveyx55%29/
app/home/main.asp?referrer=default>


Philosophical Transactions of the Royal Society of London, v. 88,
(1798) p. 469-474.


bc


p.s. to make it easier for youall:


http://www.journals.royalsoc.ac.uk/(dr5ece551054aw45zsveyx55)/app/
home/issue.asp?referrer=parent&backto=journal,
90,112;linkingpublicationresults,1:120135,1
<http://www.journals.royalsoc.ac.uk/%28dr5ece551054aw45zsveyx55%29/
app/home/issue.asp?referrer=parent&backto=journal,
90,112;linkingpublicationresults,1:120135,1>


p.p.s As written by John Stong, JB's recollection isn't quite it. --
Cavendish was confirming Newton's estimate of the earth's density.

jbellina wrote:


As I recall, Weighing the Earth was the title of the paper he wrote
about his experiment.

Joseph J. Bellina, Jr. Ph.D.
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556

On Oct 31, 2006, at 10:38 PM, carmelo@pacific.net.sg wrote:




Mike VanAntwerp wrote:



Does anyone have any lab activities or advice on teaching a unit on
this? I'd appreciate any help with this.



You may want to check these websites:
http://www.hep.fsu.edu/~wahl/phy3802/expinfo/cavendish.html

Cavendish's Experiment was designed to determine the Density of the
Earth, though some called it "Weighing the Earth".

Alphonsus

_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l



_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l





_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l


_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l


_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l