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[Phys-L] Re: In the Private Universe



I actually ask that question with four different orbital shapes using our interactive response
system right after discussing ellipses and the concept of eccentricity. You are correct, no one
picks the near perfect circle. Everyone either picks the most extreme ellipse or the second most
extreme. I then put up a table that shows the values of the eccentiricites for all of the planets.
Students then comment that they were amazed that things aren't as pictured in their books.

On the other thread about lightbulbs....
I have started drawing light bulbs in circuits with one line going to the bottom contact and one
line going to the threaded metal contact. I hope that helps convey the idea. I find many of my
students are visual learners. Well drawn graphics are important.

Take care,
David Marx
Illinois State University

I agree completely. It is interesting to see what you get when you ask
people which of three pictures is the best illustration of the earth's
orbit around the sun. The near circle, an elongated ellipse with the
sun at a focus or an elongated ellipse with the sun in the center.
Almost no one picks the near circle.

joe

David T. Marx wrote:

To me, the source of this mistake is the textbooks. The Earth is always
shown from a side view with a very elongated ellipse and the point is made
that the sun is at one of the foci. What other conclusion do we expect
students (and often their teachers) to draw from this other than the mistaken
explanation for the seasons?


On 22 Feb 2005 at 16:10, SSHS KPHOX wrote:



Forum for Physics Educators <PHYS-L@list1.ucc.nau.edu> on Tuesday,
February 22, 2005 at 9:56 AM +0000 wrote:


I think the power of the piece about the seasons rests not just in the
notion that these graduates got it wrong, but that the reason they got
is wrong may be the way they constructed their belief based on a
mistaken notion of the earths orbit coupled with their experience of
being warmer when you are close to something hot.


In addition, I have come to the conclusion that there are many things in
my life that I have "learned" and "understood" but in the long lapse of
time when I have not used the idea it fades. These graduates were thinking
of other things and had not pondered the seasons for some time. I suspect
there is smilar truth about the light bulb.

How fluent are we today in the language we "learned" in high school?
People who live abroad learn the language but when back home it fades.

What do trees do to gain mass?

I found the tapes and discussion interesting even compelling, but the
starting test of learning a bit shaky.

Ken Fox








--
Joseph J. Bellina, Jr. Ph.D.
574-284-4662, 4968
Saint Mary's College
Dept. of Chemistry and Physics
Notre Dame, IN, 46556