Popcorn pops because the water inside flashes to steam and expands. If you put the system under sufficient pressure it won’t do this … until the pressure is released, and all of the popcorn pops at the same time.
Monthly Archives: September 2011
Gimme an "A"! No, Really, Gimme an "A"
People who were doted on in childhood, driven a mile to Cross-Country practice, aren’t going to accept spending four years someplace where they aren’t comfortable and emotionally supported. We began to see a Vice-President of Student Success, a Residential Communications Coordinator, a Coordinator of Learning Immersion Experiences, a Director of Intramural Athletics. And a sushi chef. The next thing you know, it takes two hundred thousand dollars to have a proper college experience. But hey, cheer up. At least you know they’ll graduate with an A average.
You Shall Not Pass!
Chad addresses the issue of the greenhouse effect in your car, and whether putting a sunshade inside or outside matters: Greenhouse Physics and Car Shades
In the first comment we find the following question
Does car window glass block IR?
to which Chad answers
I like the idea of testing this with a piece of glass and a heater. You could probably do it with a toaster or an electric stove and a Pyrex baking dish (don’t put the dish directly on the burner, though, because they can explode that way)
Here you go. I had a beaker rather than a baking dish, and I used the IR thermometer I demoed a few months ago
You can see that the filaments are heating up, but when the beaker is put in place, the temperature drops to ambient. So it blocks basically all of the IR in the region of sensitivity of the device.
If You Love Them, Set Them Free
There’s a great discussion in Griffiths book on electromagnetism (typical book used for junior/senior course for physics majors) about what happens to free charges inside a conductor. He discusses how they will always find their way to the surface, distributing themselves to cancel the field inside the conductor. If they don’t do that, there will be a residual field to push more charges around. This happens until the field is totally cancelled. In a footnote he mentions how this surface effect only happens in 3D. In lower dimensions, like charges on a plate, say, the charges don’t necessarily go to the boundary.
Some neat simulations of both 3-D and 2-D cases.
Watching the World Go By
A time-lapse taken from the front of the International Space Station as it orbits our planet at night.
via The Bad Astronomer, who makes a recommendation
Make sure you set it to the highest resolution, then make it full screen. You’re welcome.
It's Hammer Time, but I Can't Touch This
Enigma machine to go under the hammer
A version of the three rotor Enigma machine — used by the German military to encrypt messages, the code of which was subsequently cracked by a team at the legendary Bletchley Park complex — will be auctioned at Christie’s on September 29.
The last one sold for more than $100k, which is just a bit outside of my price range.
The Greenwich Time Lady
Ruth Belville sold time. Each day she would set her watch by the Greenwich clock in London and then charge a fee for the privilege of looking at her watch.
Add “time” to that list of socialist things that people take for granted.
Contemplating Conjurors
To find out how the craft works, Jones spent two years inside Paris’ thriving world of magic. He acquired mentors, passed an examination to join France’s largest magic association, and has emerged with a new book about the experience, Trade of the Tricks, published this month by the University of California Press.
That's Minute Physics, not Minute Physics
via @occam98, who describes this as “The Vi Hart of physics, who speaks a bit more slowly, too”
Wazzap?!
Reminiscent of my navy days; when the enlisted students would walk around outdoors they had an uncanny knack of separating themselves into individuals or small groups, and you would have to return their salutes as you/they walked by. They only called me “Sir” though, not “My Lord”.