What would happen if a cue ball struck a rack of 15 perfectly round, frictionless billiard balls, exactly head-on?
An Interactive Space Simulator "Smash planets together, introduce rogue stars, and build new worlds from spinning discs of debris. Fire a moon into a planet or destroy everything you've created with a super massive black hole. You can simulate and interact with our solar system: the 8 planets,160+ moons, and hundereds of asteroids, the nearest 1000 stars to our Sun, and our local group of galaxies." [31Mb, Windows only, sorry, but see inside for similar Mac and Linux apps] [more inside]
An interesting set of videos demonstrating the state of liquid and particle systems simulation for use in movies, games, etc. It's the work of Ron Fedkiw, a computational physicist and consultant for ILM^ , who worked with his students to create all sorts of other interesting CG creations.
Ripple Tank Simulation is a delightful, mesmeric java applet simulation of a ripple tank. It demonstrates two dimensional wave phenomena such as interference, diffraction, refraction, resonance, phased arrays, and the Doppler effect (do try the 3D view). From Paul Falstad's fantastic collection of Math, Physics and Engineering Applets.
Cosmic ray air shower simulations (do not miss the movies)
Rekkaturvat: You've already pushed a hapless dummy down the stairs. Now you can see what happens when that same guy gets behind the wheel - or at least inside the cab - of a truck speeding toward a wall. Scant on documentation, but not hard to figure out (the 1 and 2 sliders control the position of two ramps). Anyone find a good technique for a high score? (2 MB Windows .exe)
A computer aided simulation builds a spiral galaxy from its beginning. In all, 390,000 particles were placed in an arrangement similar to a newborn galaxy. The end result after three months is an event that is believed to take billions of years to occur. (animation)
Bored? Maybe this little doo-hickey will entertain you for some time. It sure did for me.