Hello,
It’s very interesting the tutorial about gravity
http://www.kirupa.com/developer/actionscript/gravity.htm
I would like to know how to do this exercise with several balls falling down randomly.
Thanks for your help.
Just put several balls on the scene, or duplicate the ball clip, and set random speedx and speedy values for each 
Thank you Ilyas,
I am new in Action Script and I wanted to try it duplicating the movie and I have already done it.
I think it was not necessary to set speedx
Thanks again.
Cheers
