NetLogo Models Library:
Sample Models/Chemistry & Physics/Mechanics

(back to the library)

Random Balls

Run Random Balls in your browser
uses NetLogo 4.1
requires Java 5 or higher
(system requirements)

Note: If you download the NetLogo application, every model in the Models Library (besides the Community Models) is included. If you have trouble running this model in your browser, you may wish to download the application instead.

WHAT IS IT?

Random Balls simulates a frictionless billiard table. The balls are drawn in green. They move in straight lines and bounce off the walls but not off of each other. The center of mass is drawn in white and leaves a red trail.

HOW TO USE IT

Select the number of balls to be used, then push SETUP. Push GO to run the model.

THINGS TO NOTICE

Watch how the center of mass moves for a while. Is there a pattern? Is there a region in the box that it stays within?

THINGS TO TRY

Use the speed slider to watch the model in slow motion. Also try fast forwarding it.

Run the model with a lot of turtles. What happens to the motion of the center of mass? Why? Now run it with only a handful of turtles. (Try it in slow motion.) Now what happens and why?

Let the model run for a while. What do you notice about how much time the center of mass spends at different distances from the origin (its frequency distribution)?

Push SETUP, then in the command center, enter:

     ask balls [set heading 60]

This points all of the turtles in the same direction. What does the center of mass do now? Try other headings.

EXTENDING THE MODEL

Presently the balls don't bounce off each other. If they did, would it make a difference in the behavior of the center of mass? Try it.

HOW TO CITE

If you mention this model in an academic publication, we ask that you include these citations for the model itself and for the NetLogo software:
- Wilensky, U. (1998). NetLogo Random Balls model. http://ccl.northwestern.edu/netlogo/models/RandomBalls. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
- Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

COPYRIGHT NOTICE

Permission to use, modify or redistribute this model is hereby granted, provided that both of the following requirements are followed:
a) this copyright notice is included.
b) this model will not be redistributed for profit without permission from Uri Wilensky. Contact Uri Wilensky for appropriate licenses for redistribution for profit.

This model was created as part of the project: CONNECTED MATHEMATICS: MAKING SENSE OF COMPLEX PHENOMENA THROUGH BUILDING OBJECT-BASED PARALLEL MODELS (OBPML). The project gratefully acknowledges the support of the National Science Foundation (Applications of Advanced Technologies Program) -- grant numbers RED #9552950 and REC #9632612.

This model was converted to NetLogo as part of the projects: PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING IN CLASSROOMS and/or INTEGRATED SIMULATION AND MODELING ENVIRONMENT. The project gratefully acknowledges the support of the National Science Foundation (REPP & ROLE programs) -- grant numbers REC #9814682 and REC-0126227. Converted from StarLogoT to NetLogo, 2001.

(back to the NetLogo Models Library)

NetLogo Models Library:Sample Models/Chemistry & Physics/Mechanics

Random Balls

NetLogo Models Library:
Sample Models/Chemistry & Physics/Mechanics