What are you? Student? Teacher? Employee?
Is it your job to make applets?
I am a physics professor at Dept. of Physics, National Taiwan Normal University.
I love physics and I enjoy the fun of physics. I hope my applet can help others to enjoy the fun of physics,too! 

If you have installed EJS. Click right mouse and select "open EJS model" to open EJS,
and you will find what variables are defined, what kind of equations are being used in the simulation.
You can change the code and click green button to generate new simulation,too!
Welcomed to the world of EJS ;D

The first time the applet is loaded I get only a black screen.
I have similar problem if I open too many tabs, or browser use too much memory/resources.
And the size of EJS created jar are about 1.5M for fully function code (user can create animated gif or do curve fitting... etc when you run jar file locally) so it also take time to wait for broswer to download full size code from our server.