Here is a EJS version of the simulation similar to the one at http://faculty.ifmo.ru/butikov/Projects/Falling_bodies.html

The force for the particle is assumed to be $\vec{F}=-b\vec{V}-\vec{g}$.
You can adjust parameter b and restitution coefficient with slider.

The id slider control which particle will be modified when x,y,z,vx,vy,vz are adjusted with slider.

You will find "size effect" when b>0. i.e. smaller particle slow down faster.

Click [eye]

/htdocs/ntnujava/ejsuser/2/users/ntnu/fkh/particlesingravity3D_pkg/particlesingravity3D.propertiesFull screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
Download EJS jar file(1541.2kB):double click downloaded file to run it. (6 times by 6 users) , Download EJS source (2 times by 2 users) View EJS source

[/eye] to view simulation.