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Easy Java Simulations (2001- ) => Collaborative Community of EJS => Topic started by: lookang on April 04, 2010, 11:24:28 pm

Title: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on April 04, 2010, 11:24:28 pm
Kepler System Model written by Dr. Todd Timberlake
Access Rights: Free access
License: This material is released under the Creative Commons Attribution 3.0.
Rights Holder: Todd Timberlake
Keywords: EJS, Earth, Easy Java Simulations, Kepler, OSP, Open Source Physics, Sun, celestial globe, celestial sphere, elliptical, orbit, orbit
The Kepler System model simulates Kepler's final theory of planetary motion. In this theory the planets orbit in ellipses with Sun at one focus (Kepler's First law). These elliptical orbits are not necessarily all in the same plane. A line from Sun to the planet sweeps out equal areas in equal times (Kepler's Second law). The square a planet's period is directly proportional to the cube of the semimajor axis of its elliptical orbit (Kepler's Third law).  The simulation shows Earth's orbit around Sun, as well as the orbit of one other planet. The user can choose to show one of the five visible planets (Mercury, Venus, Mars, Jupiter, or Saturn), or a fictitious planet. The top window shows the orbits of the planets around Sun. The view can be changed by clicking and dragging in the window and a zoom slider is provided to zoom in or out. The bottom window shows the view of Sun and planet against the background stars as seen from Earth.

i will be remix this into applet for the inquiry based learning of  F=GMm/r^2 and T^2 proportional to r^3 based on data.

Title: Re: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on April 04, 2010, 11:26:24 pm
From a teacher:
We are looking at student develop F=GMm/r^2 and T^2 proportional to r^3 based on data and hence the latter can be derived from the former. I do know one method where students can use a generic approach to find the relationship between 2 variables (see attached). I guess an applet where students develop F=GMm/r^2 is useful.

Possible lesson flow:

    * Divide group of 4 students to
          o interact with applet and develop procedure to find out the attractive force between 2 masses (1/2 hr)
          o manipulate data to obtain T^2 proportional r^3 (1/2)
    * Students to find out the way to relate the two formula through circular motion (20 mins)

1 added t and realized t/2 is the actual time in years http://www.compadre.org/osp/items/detail.cfm?ID=9757&S=2
2 added r the instantaneous distance of planet center to Sun center to allow students to determine the mean distance.
3 fixed a bug with the Mars select radio because after UserDef and try to select mars again, it can't. to fix this bug, just add
selectMars ();
to the Action Off.
4 made the radiobuttons planet no deselect = "true" so that the radiobutton looks selected even if you select it twice.
5 added pictures of real planet courtesy of Nasa to all planets,
6 fix/disable a code "_view.orbitDrawingPanel3D.setScaleFactor"  that does not work on Ejs4.3
   // error in Ejs4.3
 // _view.orbitDrawingPanel3D.setScaleFactor(scale,scale,scale);
7 redraw the trace on 3D panel
8 add extra planets: uranus, neptune, pluto on both view
9 combine the a, e, i, $\Omega$, $\omega$ into the bottom view
10 fixed the bug in evolution page  to 2*Math.PI*(1+e*Math.cos(phi))*(1+e*Math.cos(phi))/Math.pow(a*(1-e*e),1.5) so that time is correct is years.

useful data

Title: Re: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on April 07, 2010, 08:04:05 am
trying to add real picture taken by Nasa into the Ejs model by Dr Todd Timberlake
Sun taken from Nasa http://www.noaanews.noaa.gov/stories2004/s2337.htm used Gimp http://www.gimp.org/ to make the background transparent and save as png

http://www.physorg.com/news129399704.html Mercury surface taken by Mariner 10. Credit: NASA

http://nssdc.gsfc.nasa.gov/thumbnail/planetary/venus/venusglobe.gif Hemispheric view of Venus produced by Magellan, courtesy of Nasa.

http://nssdc.gsfc.nasa.gov/image/planetary/earth/apollo17_earth.jpg View of Africa and Saudi Arabia from Apollo 17. Probably the most requested picture of the Earth, this picture was taken by the Apollo 17 astronauts as they left earth orbit en route to the Moon. Taken on Dec. 7, 1972, it was the first time that the trajectory of an Apollo mission enabled a view of the south pole. courtesy of Nasa.

http://nssdc.gsfc.nasa.gov/image/planetary/mars/marsglobe1.jpg Global mosaic of Mars. Visible in the center of this mosaic is the largest known chasm in the solar system, Valles Marineris. Reproduced from Volume 14 of the Mars Digital Image Model (MDIM) CD-ROM set. courtesy of Nasa.

http://nssdc.gsfc.nasa.gov/image/planetary/jupiter/jupiter_gany.jpg Three-color filter image of Jupiter and Ganymede. courtesy of Nasa.

http://nssdc.gsfc.nasa.gov/image/planetary/saturn/saturn.jpg Full-color view of Saturn and its rings. courtesy of Nasa.

http://nssdc.gsfc.nasa.gov/thumbnail/planetary/uranus/uranus_true_and_false.gif  True- and false-color images of Uranus.courtesy of Nasa.

http://nssdc.gsfc.nasa.gov/image/planetary/neptune/neptune.jpg Color image of Neptune showing its "Great Dark Spot". courtesy of Nasa.

http://nssdc.gsfc.nasa.gov/image/planetary/pluto/hst_pluto_charon.jpg Pluto and Charon
    Pluto and its satellite Charon as taken with ESA's Faint Object Camera on HST. courtesy of Nasa.

Title: Re: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on April 07, 2010, 02:06:09 pm
attaching more pictures

Title: Re: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on April 11, 2010, 07:00:03 pm
some of the common hits in kepler applet



Like: a lot! that is a lot to learn more.

Title: Re: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on June 22, 2011, 07:29:43 am
suggestion from teacher using this simulation.

I suggest a few things:
1) can we have a button for students to reset the duration of orbit, t? So that they can reset t easily for the different planets.

will add a button for t=0;

2) under the display option, can we have an option for 'Planet-Sun line'? So that they can 'see' the radius of orbit for planet.

good idea

3) the model shows that planets Mercury, Saturn and Pluto do not have circular orbit around the Sun (centre of circle does not seem to be at centre of Sun). Is this accurate?

real orbits are not circular and one of the focus is the Sun. the quick answer is it is accurate simulation. :)
Kepler's First Law:
I. The orbits of the planets are ellipses, with the Sun at one focus of the ellipse.(http://www.astro-tom.com/images/kepler1.gif)
Kepler's First Law is illustrated in the image shown above. The Sun is not at the center of the ellipse, but is instead at one focus (generally there is nothing at the other focus of the ellipse). The planet then follows the ellipse in its orbit, which means that the Earth-Sun distance is constantly changing as the planet goes around its orbit. For purpose of illustration we have shown the orbit as rather eccentric; remember that the actual orbits are much less eccentric than this.

Title: Re: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on June 23, 2011, 07:44:25 am
Question for teacher.

btw, if the orbits are ellipses, is the radius of orbit an average value?

yes, it is always changes, it is observable in the simulation as well.

If not, do you know how is this radius value derived for an elliptical shape?

Kepler's Third Law:
III. The ratio of the squares of the revolutionary periods for two planets is equal to the ratio of the cubes of their semi-major axes.(http://www.astro-tom.com/images/axes.gif)

In our syllabus, it is a slightly inaccurate as we assume all orbits to be circular thus our teaching of Kepler's 3rd Law is adapted to circular motion.

Title: Re: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on June 23, 2011, 12:35:56 pm
my request to teacher.

I have prepare the survey :)


hard copy or soft copy ?
hard advantage is richer comments

soft advantage is teacher no need to key in.

I am ok with hard or soft, up to u.

but the worksheet can I look at it.?

I want to capture more
1 assessment data, student's work on the worksheet,
2 test score
3 final year exam result on just the Gravitational questions as well as the whole exam scores.

to prepare for the journal paper and sharing the Research Question are.
1 Did the simulation on gravitation improve student performance in gravitational assessment in test, exams.
2 Did the students self report that they enjoy learning,
3 To what extent Did this lesson promoted self directed and collaborative learning?

Title: Re: Ejs Open Source Kepler System Model by Dr. Todd Timberlake
Post by: lookang on June 23, 2011, 01:48:04 pm
Question by teacher and Answers by me

But to know the effectiveness on assessment scores, don't you need to know their pre test scores or something to that effect?

it is too painful to collect so much useless data.
maybe position as inspire students to love physics?
do we think higher scores is meaningful?

if not, how can we conclude that the scores are better or worse than they are expected to get, in the absence of ICT intervention?
test scores,
questionaire surveys
face to face interviews with students

I have attached the question on Kepler model. It is actually part of the tutorial questions, so that students see the integration of ICT in learning rather than as a supplementary exercise.. Feel free to comment.

I will add questions to inspire them to think