Resources for COSMOS

• Projectile simuilation. How far will the cannonball go, as a function of angle. Interestingly, computing such "ordinance tables" was one of the most compelling reasons used to motivate governments to fund the development of computers (e.g. for Babbage's Differential Engine and the Eniac)
• Billiards. A momentum and friction simulation lets you play pool. Incidentally, "Ball im Loch" is German for "the ball went in the pocket".
• Satellite orbit calculator. See if you can get the satellite in orbit close to earth. This was another early use of computers back in the "space age".
• Celestial mechanics. Here you have two stars (or whatever) in orbit around each other, and you get to introduce additional bodies (e.g. asteroids) to see how they are affected. I suggest hitting "ZAP" to clear the space, then click a bunch of times somewhere to introduce some asteroids. Now see if you can manage to get an asteroid that will remain in orbit. (Moving the "+" in the upper left-hand box affects the initial velocity of the asteroids.) NASA uses computers to figure out how to use planets like Mars and Venus to "slingshot" satellites to more distant planets.
• Molecular dynamics. This might not be much fun, but it shows an incredibly important application of computers - simulating the behavior of the atom that form a molecule. You can drag the atoms to different locations, then repeatedly click "Energy Minimize" to see how they move back towards a stable shape. Such programs are used by computational biologists to, for instance, to try to determine the structure of proteins, which can help design drugs.
• Aerodynamics. I haven't totally figured this one out, but it seems to show how much lift an airplane wing of different shapes produces. In any case, making more fuel-efficient cars and airplanes is an important application of computers.
• Fission reaction. One of the major problems faced by the Manhattan Project in developing the atomic bomb during WW II was to determe how much uranium was needed to sustain a nuclear reaction. They didn't have computers to do simulations like this one, but they had hundreds of people doing calculations by hand. (Actually, they also had some incredible mathematicians figuring out how to get the answer without simulating zillions of particles.) Today, the most powerful supercomputers are in the ASCI project, whose mission is to determine, by simulation, if our nuclear weapons will still work, since by international treaty we can't actually set them off.
• StarLogo. This looks like it might be fascinating, but I haven't actually downloaded the software to try it out. The general idea is you program how each little agent behaves (like bees or cars), then StarLogo simulates a whole bunch of them to show what their collective behavior is. (This is really how every system in the universe works!) Click on the "Projects" button to get examples of what StarLogo supposedly can do.
• Stacking books. This isn't really a very good example of a physics simulator, but it does raise the amusing mathematical question (which you have learned enough in school to answer) as to whether there is a limit to how much of an overhang you can get with a pile of books as high as you want.

Here are the files for the JavaScript exercises. Click on each one to display the page. Then use the "View" menu and click on "Source". This should put you into NotePad, viewing the code that created the page. There are suggested exercises at the top of the files.

• 1.html
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• 9.html