Love Grant's demos, and anyone interested should check out some of his other ones, too: <a href="http://sites.google.com/site/kotsoft2/physicsdemos" rel="nofollow">http://sites.google.com/site/kotsoft2/physicsdemos</a><p>One request: if possible, please label links that go directly to Java applets. For a lot of us, opening a page with a Java applet on it involves maybe a 20% shot at crashing the browser, and even in the best case scenario, my MBP freezes up for ~30 sec while the piece of crap Java plugin gets started up.<p>Which I'm fine with if I'm warned, and in this case I'd click through anyways.