Kepler Motion

[Daniele]

Hi,
I found your applet very usefull and clear. I am an astronautical engineer and I am coping for the first time with Java. I used to program in MATLAB/SIMULINK environment, therefore the point of view is quite different because of the Java Object Orientation. I would like to ask to the author of the applet some additional detail about the integration of the equations of motion:

1. What kind of numerical integrator did you use (RK4, Euler,...)?
2. Is it possible to integrate non linear ODE of the second order (i.e. the equations of motion for the restricted three body problem) or it is necessary to transform every equation of the second order in two equations of the first order?
3.I went through the source code of the applet, but it is quite confusing for a new Java user; is it possible to point out the section of the code where the integration is performed?

I do apologize if these questions may seem elementary, but the approach needed to program in Java is completely different from that one needed in MATLAB/SIMULINK, where the integrators are black boxes.

Many thanks in advance for any help.

Best regards,
Daniele

[Fu-Kwun Hwang]

1. Almost all the simulation were integrated with RK4.
2. Most of the second order ODE should be able to break into two first order equation.
3. I would suggest you try Easy Java Simulations (EJS).
The code you got was created almost 10 years ago with JDK1.0.2.  I switch to EJS since 2001 and it will be much easier for non-programmer to create simulation.

[Daniele]

Hi!
Thank you very much for your prompt replay. At the moment I am using eclipse as IDE, do you think it is a good way to start?

I think that most of the problem is to understand the way an OO application works: do you think it would be possible to you to prepare a simple simulation for a 3D circular orbit around the earth? That would be a nice way to start, in order to implement new features like elliptic orbits, perturbations due to the earth oblateness, drag, third body and, most of all, understand the technique involved in this example.

Best regards,
Daniele Romagnoli

[Fu-Kwun Hwang]

Eclipse is a good IDE for general purpose programming. But EJS is designed for science teacher or students. Please check out
Easy Java Simulations: a software tool to create scientific simulations in Java which is written by EJS original author: Francisco Esquembre
and do not forget to visit Offcial EJS WiKi Page

I think you will like it!

[pdnoerd]

Nice demonstration

Some spelling errors:

(Java Simulaions in Physics)
should be
(Java Simulations in Physics)  (you left out a "t")

"16 centry" should be "16th century"

"Danish bobleman Tycho Brahe" should be "Danish nobleman Tycho Brahe"

Also, someplace I saw "summerized" which means "made ready for summertime" but you want "summarized".  To "summerize" is to fix the air conditioner, for example.

Sorry - I know you start with a different language - just trying to help
Peter

[Fu-Kwun Hwang]

Thank you! I have corrected the message according to your suggestion.

[Fu-Kwun Hwang]

Registed user can get files related to this applet for offline access.
Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
If java program did not show up, please download and install latest Java RUN TIME

Try to compare the above motion with the following model.

Registed user can get files related to this applet for offline access.
Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
If java program did not show up, please download and install latest Java RUN TIME

[sharonk868]

Could you at least explain what you want to create? What kind of simulation? What you want to show in the simulation?
Do you have the formula now? What are the form of your formula? What is your model for the simulation?
There are so many information which you did not provide.
I can not read your mind.

I think you also need to learn: How to ask a question effectively? How to explain your problem?
If I do not have a very clear picture of what you really want to do. There is no way I can help.

I also think so.
Thanks you for the post.
Hi guys, Im a newbie. Nice to join this forum.
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[TraceyTrias]

Thanks a lot. It is very helpful to me... I really needed that.. Thank you so much.

-*-

[cjamesha]

You should have received source code in your email box now.

I want to start writing simulation for electronic circuits. Could you send me source code for keplers laws?

C. James

[Fu-Kwun Hwang]

You can download it by yourself (attachement file under the first message).
However, the code was written more than 10 years ago with JDK1.0.2.

I would suggest you to lean EJS. It will be much easier to create simulation with EJS.
There are several circuit related simulation created with EJS, Please check out Electromagnetism board under Easy Java Simulations (2001- ) category.

[physics4ever]

hello
would you send me the code of the kepler's motion applet ,
i am in need for it
thanks for your help 

[Fu-Kwun Hwang]

The source code is available as attached file under 1st message (where you saw the simulation).
May be you did not look at the whole message so that you did not find it.
Please download it by yourself.

[physics4ever]

Thank you for you note and I have downloaded it .
I appreciate your help.
sorry for bothering you. I haven't noticed the attachement from the very beginning
 

[jenny.smith]

Well i have lost doubt regarding the Kepler Motion,but after going through post its sorted out great work.

[sammys4travel]

hi,
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[diinxcom]

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Just Bookmark..
I am new here.. I hope can get many thinks from this forum...

[seyf-educ]

thank you for this post