Category Archives: Useful

(News) Flash

You should really keep paying attention to the speed limit while pondering why the heck someone flashes their brights at you even though your headlights can’t possibly be broken because you just had the car checked at the garage the previous day.

It turns out that you remember the other reason why some drivers flash their brights at you in Germany a few seconds later when a blinding red flash indicates that you have just been photographed by the police: The driver was trying to tell you that there’s a speed trap around the corner.

This is what happens if you’re taking the scenic route through the Rhine valley instead of using the autobahn for your way home from work as usual. At least I was only going a little bit over the speed limit; we shall see if I get a ticket or not.

(Related: Why did you flash your brights at me tonight?, Headlight Vocabulary.)

Simulate your own solar system – and more!

Sometimes MetaFilter has links to sites right up my alley: Physics simulators. Lots of physics simulators.

“PhET – Physics Education Technology offers this astoundingly large library of online physics simulations.

Play orbital billiards. Land on a cheesy moon. Experiment with sound. Or try more advanced quantum physics simulators. Still bored? Try the “cutting edge” catagory. Here’s the complete index. (Warnings: Frames, Flash, Javascript, Java applets, graphics, sound, quantum timesuck.)“

I especially like the orbit simulator because I once had to program one in university. During my third semester (I was still aiming for a master in physics back then) I took a course on theoretical mechanics, and we had to write a program that simulated the paths of the moon relative to the earth and the sun. The masses and velocities of the objects were adjustable.

It took me weeks and weeks to finish because I had never programmed anything serious before, but it still didn’t calculate correct paths the day before the deadline, so I had to ask for some more time. Two frustrating afternoons later, I finally found the sign error in one of the formulas… Sigh.

I just realized that this must have been in February of 1996, so more than a decade has passed since then. I guess they do different programming tasks in theoretical mechanics now that you can just download applications like this from the web. Which is a good thing for me because now I can use these spiffy simulations in my lessons instead of my amateurish ones. I’m sure the students are going to appreciate it.

Anziehend

Jede Menge sehr starker Magnete – hergestellt aus Neodym-Eisen-Bor (NdFeB) – findet man bei Supermagnete.de, einer kleinen aber feinen Firma, die zwar in der Schweiz basiert ist, aber auch aus und nach Deutschland versendet. Zu jedem Produkt – vom kleinsten Mini-Magneten bis zu Pinnwand-Magneten im Edeldesign – findet man gute Beschreibungen sowie Fotos, die von der zum Teil unglaublichen Haftkraft der Magnete zeugen oder die vielseitigen Anwendungsmöglichkeiten veranschaulichen. Nicht nur verspielte Physiklehrer werden in diesem Online-Shop fündig… ;-)

Eine etwas kleinere Auswahl zu vergleichbaren Preisen findet man beim Magnetladen.de.

Full disclosure: Bei Supermagnete.de habe ich schon Magnete bestellt (netter schneller Service, einige kleine Magnete zum Spielen gab’s gratis dazu), beim Magnetladen allerdings noch nicht.

P.S.: Mit diesen starken Magneten kann man übrigens den einfachsten Elektromotor der Welt bauen, den ich vor längerer Zeit bereits erwähnt und verlinkt hatte.

Schöne Links beim Schockwellenreiter klauen

Jörg hat heute gleich mehrere Links, die es sich lohnen zu klauen:

MathPuzzle.com, the puzzling weblog of recreational mathematics offers Sam Loyd‘s Cyclopedia of Puzzles or Sam Loyd’s Cyclopedia of 5000 Puzzles, Tricks, and Conundrums (With Answers) – among many other things worth checking out! (Beim Schockwellenreiter hier gefunden.)

Und:

“Für die kleine Formal zwischen durch ist die Freeware PDF Equatation sehr hilfreich. Sie bietet ein Eingabefenster, in dem schnell die LaTeX-Befehle für eine Formel eingegeben werden können. Das Programm erstellt dann eine PDF-Datei, die sich in den meisten Text verarbeitenden Programmen unter OS X als Grafik weiter verwenden läßt.” (Quelle)