Author Topic: Brownian Motion  (Read 523813 times)

Fu-Kwun Hwang

  • Administrator
  • Hero Member
  • *****
  • Posts: 3062
    • Enjoy the fun of physics with simulations
Brownian Motion
« on: January 29, 2004, 09:38:56 pm »
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


Qualitative evidence of the microscopic nature of gases is shown by an effect called Brownian motion.
This java applet shows Brownian motion for gas molecules.
(Gas molecules in a container continually collide with one another and with the walls of the container.
    Keep in mind : this is a slow motion and magnified view in a small area.

Please check out Collision 2D for how to process collision between two particles.

    Each circle represents a gas molecule.

    N is the total number of molecules in the area.
      Enter value into the Text Field and press RETURN.

    m2/m1 is the mass ratio of red ball to gray ball.

    (Try it, and find out the difference)


    Press + will have a smaller time interval. (faster motion)

    Press - for slower motion.
    Click trace check box to show the trace for one of the molecules (red).
      Click it again to turn it off and clear the screen.


    Right Click to stop the animation, click it again to resume.
     While the animation is stopped, drag the red ball to relocate its position.
    If you click No boundary checkbox, particles moving to the right edge will appear at left edge again (No collision with the wall).


Here is a related youtube movie

http://www.youtube.com/watch?v=FAdxd2Iv-UA&hl


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

  • Guest
topic24
« Reply #1 on: January 30, 2004, 12:13:41 pm »
Subject: Brownian motion
Date: Sat, 5 Sep 1998 10:18:45 +0100
From: "Peter Mussard" <p.mussard@sfxavier.ac.uk>
To: <hwang@phy03.phy.ntnu.edu.tw>
The animation is good, but the text 'Green dots are velocity distribution of the
molecules' doesn't make sense.

Peter Mussard

p.mussard@sfxavier.ac.uk

  • Guest
topic24
« Reply #2 on: July 11, 2004, 07:46:34 pm »
[quote:f669a5a961="Anonymous"]Subject: Brownian motion
Date: Sat, 5 Sep 1998 10:18:45 +0100
From: "Peter Mussard" <p.mussard@sfxavier.ac.uk>
To: <hwang@phy03.phy.ntnu.edu.tw>
The animation is good, but the text 'Green dots are velocity distribution of the
molecules' doesn't make sense.

Peter Mussard

p.mussard@sfxavier.ac.uk[/quote:f669a5a961]
but the text about "the text 'Green dots are velocity distribution of the
molecules'doesn't make sense" doesn't make sense. what text about green dots? what tokking u?

  • Guest
topic24
« Reply #3 on: July 11, 2004, 07:55:58 pm »
sometimes the red ball gets stuck in the top left corner and won't move at all. Why? (i tried noboundary too, but the ball stayed still.)

ibum

  • Newbie
  • *
  • Posts: 0
topic24
« Reply #4 on: July 11, 2004, 08:01:54 pm »
[quote:490d1a9613="Anonymous"][quote:490d1a9613="Anonymous"]Subject: Brownian motion
Date: Sat, 5 Sep 1998 10:18:45 +0100
From: "Peter Mussard" <p.mussard@sfxavier.ac.uk>
To: <hwang@phy03.phy.ntnu.edu.tw>
The animation is good, but the text 'Green dots are velocity distribution of the
molecules' doesn't make sense.

Peter Mussard

p.mussard@sfxavier.ac.uk[/quote:490d1a9613]
but the text about "the text 'Green dots are velocity distribution of the
molecules'doesn't make sense" doesn't make sense. what text about green dots? what tokking u?[/quote:490d1a9613]
what tokking u? sounds like me!
and btw, sometimes the red ball gets stuck in the top left corner (as i have said earlier), and sometimes it disappears!

Fu-Kwun Hwang

  • Administrator
  • Hero Member
  • *****
  • Posts: 3062
    • Enjoy the fun of physics with simulations
EJS verison of Brownian Motion
« Reply #5 on: May 16, 2005, 03:53:33 pm »
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

The following is new verision of brownian motion created with EJS.

If you want to know how to process collision between two particles,
please check out EJS version of Collision 2D.





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

kuschei

  • Newbie
  • *
  • Posts: 1
  • physics
topic24
« Reply #6 on: July 03, 2005, 06:05:12 pm »
:)

alphadp

  • Newbie
  • *
  • Posts: 3
very good work
« Reply #7 on: March 22, 2006, 05:11:19 pm »
fine fine fine...
but where is the Applet files of the new verison
i want it :shock:
will you send it to me (email)
thank you :D

Fu-Kwun Hwang

  • Administrator
  • Hero Member
  • *****
  • Posts: 3062
    • Enjoy the fun of physics with simulations
Re: Brownian Motion
« Reply #8 on: March 05, 2007, 03:40:29 pm »
Just click "download applet files for offline use" button, if you login to the forum.

vvelemir

  • Newbie
  • *
  • Posts: 3
Re: Brownian Motion
« Reply #9 on: April 10, 2007, 12:35:42 am »
Thank You. :)

Doc_B

  • Newbie
  • *
  • Posts: 8
Re: Brownian Motion
« Reply #10 on: April 25, 2007, 04:14:45 pm »
I am doing alot of research on financial markets. Is it possible to create for this 2 dimensional plot a 1 dimensional brownian function with time on x-axis?

thx a lot

Fu-Kwun Hwang

  • Administrator
  • Hero Member
  • *****
  • Posts: 3062
    • Enjoy the fun of physics with simulations
Re: Brownian Motion
« Reply #11 on: April 26, 2007, 05:09:03 pm »
You want the horizontal axis to be time, however, what will be the vertical axis?  (Click load ejs as signed applet and make some modifications- add another plotting panel and add some traces , then you will get what you wanted! ).

Tell me in more detail what you want, and I will show you how to do it with ejs.

Doc_B

  • Newbie
  • *
  • Posts: 8
Re: Brownian Motion
« Reply #12 on: May 09, 2007, 04:37:24 pm »
I would like to see somthing like this:

http://www.mscf.uky.edu/~mai/java/stat/brmo.html

on the left the brownian motion and on the right a one dimension plot of it.

thx a lot for your help...

P.S.: I cannot get the source code for the java applet from the other weblink.
I need this applet a little bit larger to see the fine structure.

Fu-Kwun Hwang

  • Administrator
  • Hero Member
  • *****
  • Posts: 3062
    • Enjoy the fun of physics with simulations
Re: Brownian Motion
« Reply #13 on: May 11, 2007, 05:51:17 pm »
You can add any diagram easily with ejs.
1. Click "loaded ejs as signed applet"
2. You will need to give permission for browser to load ejs into your computer (If it is the first time you click that button)
3. When EJS is fully loaded (It will take a few minutes for first time user).
4. You will find introduction/model/view panels. You can find out how the variables are defined, what kind of equations were used,...etc from model panel. The x,y coordinate for the big particle is defined as px,py in the model. The time is defined as t.
5. Click View panel to add a new window to display diagram.
 1) add a dialog window (You can adjust the size and location).
 2) add a plottingPanel to plot diagram.
 3) add a trace element to display trace for (t,py)
 4) assign variable t, py as x,y properties for trace.
 5. Click run button to create a new simulation with the diagram you want.

I have created a flash motion to demonstrate the above steps. However, the interface were shown  in Chinese Because I am running it with my Chinese OS.

You can also save the ejs locally.

Doc_B

  • Newbie
  • *
  • Posts: 8
Re: Brownian Motion
« Reply #14 on: May 12, 2007, 02:47:25 am »
Thanks, thanks a lot for your help. I watched your Flash Animation 15 times to set all parameters correctly. But lastly it will not run. I got 100 errors. After playing around with it and tested this applet without modifying anything, it gave me also these errors.
What I did was: I loaded the ejs by clicking on the "load ejs as signed applet" button and then hit the right green arrow. The applet was not runnig and I got these Error-Messages in the lower subgraph.
Perhaps I have something to change on my computer settings.

Thanks for your help....