All of the physlets here are designed to work with Mozilla, and not just IE. Therefore they must be manually initialized. You will need to click on an a pink button after the web page appears in your browser, like this one:
But, as always with Java applets, you may need to wait a bit to retrieve the applet across the internet, and for your computer to load it.
I have only a few physlets here now. I hope to have dozens in the future. The pages may be changing daily, if not hourly. Mozilla users should set Edit>Preferences>Advanced>Cache to "every time I view the page".