There a limits to how many particles i can created to collide with the blue ball. I tried to increase the amount to 150 and higher and flash started to lag. Thus, i keep my particles number to 100 as my main purpose is to illustrate how brownian motion works.
// create movieclip to store lines drawing for brownian motion
createEmptyMovieClip("line_mc",getNextHighestDepth());
line_mc.lineStyle(0,0xFF0000,100,true,"none","none","miter",1);
line_mc.moveTo(ball0._x, ball0._y);
// create num of balls var numBalls:Number=100; for(var i:Number=1;i<numBalls;i++){