Roland Roberts's blog

Asteroid Impact in Nubian Desert Tracked

Science News is reporting on a first of its kind: an asteroid that was tracked all the way to its impact on Earth.

The asteroid was apparently about the size of a car (hmm, would that be a Hummer or a mini-Cooper?) and since the trajectory was well-tracked, the impact site in northern Sudan was found an much of the debris recovered for study.  The ony scary part is this sentence:

Open Source Physics Educational Java Tools

Well, it's good news bad news time.  I was excited to find these via an article in the Physics Teacher.  Clearly, I haven't been paying attention, because they've been mentioned before, but the item which caught my attention was an article that used a program called Tracker to analyze 2D motion.  I immediately thought of using for projectile motion (what is the muzzle velocity of a Nerf® gun?).

C/2007 N3 Lulin from Brooklyn

Well, sort of.  I got out briefly tonight with my wife's Canon 12x36 IS binoculars (that's Image Stabilized).  The position of Lulin is easy enough to find with Saturn less that 6º away and two reasonably bright star nearby to help zero in on its location - Leo 59 at mag 5 and Leo X-63A at mag 4.6.  Leo 59 is only half a degree away.


For his science fair project, Jonathan investigated pendulums.  His
hypothesis was that how fast the pendulum swings, its period, should
depend on how heavy it was.  So I arranged to have 1-inch diameter
pendulum bobs made of copper, steel, and wood.  We suspended each from
a horizontal beam, carefully measured so they were all the same length,
then swung them back in synch.

How Fast is Sound?

A few months ago, I read an article in The Physics Teacher (published by the American Association of Physics Teachers) on measuring the speed of sound using a couple of microphones hooked up to a computer's line-in jack.  Apart from having to make a trip to Radio Shack to buy some parts to convert two standard unpowered microphones into a pair of powered microphones for stereo input, the process was amazingly straightforward.  I did a quick proof-of-concept in the dining room one evening and go

Milky Way Gets a Little Bigger

There's a New York Times Science article from yesterday reporting on recent measurements indicating that the Milky Way, our home galaxy is bigger than previously thought. We now qualify as a peer of the Andromeda galaxy. The critical measurement was how fast we revolve around the galactic center. The faster we're going, the more massive our galaxy must be to hold us in.

Math Evolver, needs to evolve a bit more....

Math Evolver is a game by DimensionM used to teach pre-algebra to middle school students.  While perhaps not quite as exciting as Halo, its very good.  Good enough that my older son is willing to actually think in order to play the game (at least when I won't let him play Halo which, of course, requires very little thinking).


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