Ejs Open Source Brownian Motion Gas Model Java Applet by Professor Paco & Hwang, now remixed by lookang so i can learn from examining the codes legally because the condition of use is attribution of original authors.
This is a simulation of Brownian motion of a big particle (dust particle) that collides with a large set of smaller particles (molecules of a gas) which move with uniform motion in different random directions.
The Brownian motion of a particle in a liquid is thus due to the instantaneous imbalance in the combined forces exerted by collisions of the particle with the much smaller liquid molecules (which are in random thermal motion) surrounding it. http://en.wikipedia.org/wiki/Brownian_motion
The mathematical model of Brownian motion has several real-world applications. An often quoted example is stock market fluctuations. http://en.wikipedia.org/wiki/Brownian_motion