Brownian Motion Applet JavaFILE

A Brownian Motion Applet

(Quoted from Dr. Michael Fowler's web site):
This Java applet is a simple demonstration of Einstein's explanation for Brownian Motion. It shows little particles batting about a more massive one and what it would look like if you could see only the massive one through a microscope. (When the ball gets close to an edge of the "microscope", the part that disappears is shown on the opposite side - a "toroidal microscope".)

The Assignment is described below.

Your assignment is as follows.
Repeat the following experiment six times (or more if you have enough patience): write down how much time it takes for the blue ball until it first touches the green ring, when starting from the center. Average your results.
(A stopwatch is provided for your convenience.)
Next, answer: how many seconds will it take, on the average, for the ball to leave a ring whose radius is 3 times as big as the one shown? (This takes one line: you should use the fact that "the average time taken to diffuse a distance d is proportional to d^2")

Important: The "reset" button in the simulation doesn't seem to work. I find I have to reload ("refresh") the page to re-start the simulation. In some browsers, just using the Reload button in your browser will not work well, in which case you need shift-reload (keep the shift key pressed down while you click on reload).

In case you want to play with parameters, these can be changed in the source code for the page that you are seeing:
nballs: number of red balls,
averagevelocity: the average velocity of the red balls.
Increasing temperature will correspond to the red balls (which could represent water molecules) moving faster.

This is adapted by E. Sontag from: Copyright (C) 1998 Michael Fowler
Please click here for source code and GNU License details.