The Virtuosi: Microseconds and Miles
A script for figuring out the relativistic corrections of GPS satellites. I don’t use the Schwarzschild radius notation when I do it, but it’s all good. Potato, potahto (but not potatoe).
Category Archives: Physics
Here's Mud in Yer Eye
The Physics of Mud and Hair Gel
Watching things dry isn’t always the most enlightening project, but researchers publishing in the September Physical Review E have discovered some new twists to the drying process. They created three different simulated soils by mixing tiny glass beads with clay or gel and used magnetic resonance imaging (MRI) to watch as the water evaporated from the samples. The results point to the properties of the pasty material between the beads as the dominant factor determining the drying speed, an important soil property for farmers. The team also speculates that slower-drying material could be added to real soil to help it retain moisture.
Make It Un-So
The device works by shining a hollow laser beam around tiny glass particles. The air surrounding the particle heats up, while the dark center of the beam stays cool. When the particle starts to drift out of the middle and into the bright laser beam, the force of heated air molecules bouncing around and hitting the particle’s surface is enough to nudge it back to the center.
So it’s a neat effect. But …
Because this technique needs heated gas to push the particles around, it can’t work in the vacuum of outer space like the tractor beams in Star Trek.
Which won’t stop you from labeling this technique with a Star Trek term that described something that’s only vaguely similar …
Kids, Don't Try This … Anywhere
Kids Playing With Laser Pointers May Be Aiming for Eye Trouble
Sadly, this is too common, and this is just the latest incident.
He told doctors that he purchased the laser pointer so that he could pop balloons from a distance, burn holes in paper cards and burn holes in his sister’s sneakers.
…
Schmid said the boy wasn’t sure if the laser was dangerous, and he definitely didn’t know it could cause immediate eye injury.
I have a hard time connecting these two statements. Knows it would burn holes in things, but didn’t know it was dangerous.
Don't You Know You're Gonna Shock Shoot the Monkey
Rhett does the “shoot the falling target (aka monkey)” demo, and solves the kinematics. This was the demo that got me truly hooked on the idea that I wanted to do physics, after my neighbor set this demo up in his basement, albeit with a blowgun and with a cruder triggering mechanism.
Validate Me, or Someone Else
[T]his year we’re hosting our first ever physics.org web awards to give the best physics sites out there some well-deserved recognition
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Nominations open on Monday 6 September 2010, and you’ll have 6 weeks (until 10 October) to give your favourite physics sites the chance to scoop up an award.
Uncertainty Squared
Uncertain Principles: What Uncertainty Means to Me– And You, and the Universe
One of the most (if not the most) commonly maltreated physics concepts in journalism is the Heisenberg Uncertainty Principle.
[T]he origin of uncertainty really does spring from the idea of particle-wave duality rather than any ideas related to the act of measurement. It comes from the fact that, fundamentally, the position of a quantum object, like an electron or a photon, is a particle-like characteristic, while its momentum is associated with the wave nature of the object. Mathematically, the momentum of a quantum object is given by Planck’s constant divided by its wavelength (or, equivalently, the wavelength associated with a quantum object is determined by Planck’s constant divided by its momentum).
Perhaps we can start up the group Physicists For The Proper Treatment of the Heisenberg Uncertainty Principle, or PFTPTHUP (which would sound like blowing a raspberry, or Bill the Cat hacking up a furball, either of which could be one’s reaction to seeing the HUP abused in the media)
Robots Perpendicular to a Plane
A week ago it was geckos. Now, I can almost hear Samuel L. Jackson saying, “There are Mothef—— robots on this Mothef—— plane!”
Beavers … iiiin … Spaaaaace
Time lapse footage taken by Oregon State University alum Don Pettit during his time on the International Space Station. This one shows Earth from day to night.
Cool. Especially the aurorae.
Magnus-ificient
Carlos ’97 free kick no fluke, say French physicists
While their research quickly confirmed the long-known Magnus effect, which gives a spinning ball a curved trajectory, their research revealed fresh insight for spinning balls that are shot over a distance equivalent to Roberto Carlos’ free kick.
The friction exerted on a ball by its surrounding atmosphere slows it down enough for the spin to take on a greater role in directing the ball’s trajectory, thereby allowing the last moment change in direction, which in the case of Carlos’ kick left Barthez defenceless.
The researchers refer to their discovery as the ‘spinning ball spiral,’ comparing the spiralling effects of Roberto Carlos’s kick with the shorter-distance (20-25 m) ‘circular’ free kicks shot by the likes of Beckham and Platini.…
‘People often noticed that Carlos’ free kick had been shot from a remarkably long distance; we show in our paper that this is not a coincidence, but a necessary condition for generating a spiral trajectory.’
Here’s the kick in question: