I add graphic to [b] X[/b] and [b]Y[/b] so when i run simulation mass begin move by value that i set
And when touch ground return again by the same trace for second time so in graphic line become more Strong
So i think may this mix students when watch graphic work again by the same way without change value so this make me ask
To make applet work just one time only.

About  mu account i don't know really what happen i was check site normally yesterday
And 10 Minuet's before finish time my work find it in my account  so i Email you direct.
Thank you so much.