Physics
rallain | July 28, 2009Thanks to reader Cleon for notifying me of this video on youtube. Check it out.
First, some notes.
I am sure you noticed that the aspect ratio is incorrect (at least that was the first thing I noticed). The boys must have made a 16:9 video, but then uploaded it to youtube as a 4:3. This doesn't really affect the analysis, but I had to fix it. I used the awesome firefox plugin NetVideoHunter to download the video and then used MPEG Streamclip to resize the video.
Other than that, they did follow my suggestions for making videos. The camera doesn't move and is mostly perpendicular to the…
drorzel | July 28, 2009The question of who is the greatest physicist of the physicists who are household names-- Newton, Einstein, Maxwell, etc.-- has been debated thousands of times, and will undoubtedly be debated thousands of times in the future. What isn't as often discussed is the ranking of physicists who aren't in that rare group of household names-- people whose surnames are attached to equations that GRE takers struggle to memorize, but whose given names and life stories are mostly forgotten.
Well, this post is for them: The following poll presents a list of important figures from the history of…
grrlscientist | July 28, 2009tags: physics, flatland, 4th dimension, Carl Sagan, streaming video
In this video, world famous astronomer and astrophysicist, the great Carl Sagan, explains the 4th dimension. I wonder if Carl knew how funny he was? [7:15]
esiegel | July 27, 2009
Doomsday in 2012? Please, I don't even have time for that. (Check out Ian O'Neill's work for a nail-in-the-coffin of those myths.) But there is a big milestone that we will reach right around 2012.
Prior to the industrial revolution, the Earth's atmosphere was really ideal for supporting the wide diversity of life on the planet. Breaking it up into its physical, molecular contents, the atmosphere, weighing in at just over 5,100 trillion tonnes (5.1 x 1018 kilograms), was made up of the following elements (by mass, not volume):
Nitrogen gas (N2): 3,890 trillion tonnes (around 75.5%),
Oxygen…
rallain | July 27, 2009Sciencegeekgirl is blogging from the AAPT. She talks about showing something interesting to get students thinking, and here is her example:
This reminds me of Dan Meyer's What Can You Do With This stuff. Anyway, I can't help it. I must analyze this video. Plus, Fran essentially threw down the gauntlet and called me out on this move. Another reason to analyze this movie is that it is obviously fake. Elephants are one of the few animals that can't jump. Not even a little bit. They don't like to have more than 1 foot off the ground. Ok, on to the analysis. As usual, I downloaded the…
drorzel | July 27, 2009Timothy Burke notes a controversy about an NEH program that some philosophers feel tramples their discipline. In talking about a hypothetical program that would do the same for his field of history, Burke suggests something that caught my eye:
f the NEH set up a course development grant called "Time and the Past" aimed at supporting interdisciplinary courses that examined change over time but framed the grant so that ordinary history courses didn't qualify, my first impulse would be to object. Why exclude the discipline that makes that question its central concern?
But hold on a moment. What…
grrlscientist | July 27, 2009tags: physics, solid materials physics, crystal structure, packing coefficient, streaming video
In this video, a physics lecturer at the University of New South Wales in Sydney, Australia sets a challenge to the public based in his solid state physics class (PHYS3080). [9:10]
sporte | July 24, 2009I don't remember learning about plasma when I took physics, but it's amazing stuff. Last week at the Hi-Tec conference in Arizona, I got to learn how an electromagnetic field can be used to push plasma around a tube. Community college students get to play with the coolest toys!
Here's some plasma contained in a small area.
Figure 1. Plasma on the table.
Here's some plasma getting pushed around a tube.
Figure 2. Plasma getting pushed around.
Wikipedia has a very nice article on plasma and plasma displays that occur in nature, such as St. Elmo's fire. I guess if you want hands-on…
drorzel | July 24, 2009Over at Dot Physics, Rhett wonders about the role of homework in a world that includes cramster:
Then what is the problem? The problem is with my jobs. Yes, jobs. I have two jobs. My first job is to help students learn. I am a learning-faciliator if you like. I do this in many different ways. One way is to assign homework. Oh, my other job is to evaluate how well students understand the material. I have to give them some grade at the end of the semester. One obvious way to do this is with an exam or feats of strength.
Here is the question: Do you grade homework? Oh, I know what everyone says…
drorzel | July 23, 2009I've had a few conversations with other small-college folks about how there ought to be some sort of group within DAMOP for people at small colleges, given how many of us there are who do AMO physics. Nothing has ever come of it, because nobody wants to take on the administrative hassle of organizing such a thing.
Fortunately for small-college theorists, they have some people who are more willing to step up, and have formed the Anacapa Society:
The Anacapa Society promotes research in all areas of theoretical and computational physics at primarily undergraduate institutions. The Society…
pontiff | July 22, 2009Two notes from Caltech of interest:
Michael L. Roukes' group at Caltech has produced a NEMS (nanoelectromechanical system) device which can (almost) measure the mass of a single molecule (as opposed to the many tens of thousands (is this the correct amount?) needed in mass spectrometry.) Build a 2 micrometer by 100 nanometer NEMS resonator. Drop a molecule on it. The frequency of vibration of the NEMS resonator changes. Detect this frequency change. Of course vibration frequency also depends on where the molecule lands. So run the experiment about 500 times to get good estimate of the…
rallain | July 21, 2009The Anacapa Society is a professional organization promoting research in all areas of theoretical and computational physics at primarily undergraduate institutions.
If you are at such an institution, I would recommend taking a look and perhaps joining. In my views, undergraduate research is one of the best things about an undergraduate institution. What better way to learn physics than by doing physics. My institution is primarily undergraduate and I can say that although working with undergraduates has it's challenges, it has benefits also. I think it is the thing that smaller schools…
rallain | July 21, 2009So, I built a new accelerometer. Why? The jelly-jar one was just not doing it for me. Plus, the cork was starting to make the water all yellowy. It was a good start, but I can do better. What was wrong with the jelly-jar one? First, it didn't let the cork move very far before hitting the wall. Second, it was kind of hard to see exactly where the cork was. Lastly, there was no way to get a reading of the acceleration from the jelly-jar. Now, I am going to fix that.
My new design uses a sphericalish glass flask. The floating bob is anchored in (near) the center of this sphere. Here…
rallain | July 21, 2009This comes up everytime I teach physics for elementary education majors. The curriculum I use (Physics for Everyday Thinking - which is awesome) says that the colors in white light are ROYGBV (Red-Orange-Yellow-Green-Blue-Violet). Typically, I will get a student that says "Hey! What about indigo? Shouldn't it be ROYGBIV?" My first reaction to this was "huh?" Really, does it matter? Here is the spectrum you would see looking at a white light source.
You could break this into as many or as few colors as you like. So, it doesn't really matter. But this leads to a great question: Who…
drorzel | July 20, 2009I'm watching an episode of NOVA scienceNOW (eccentric capitalization makes it hip!), and Neil deGrasse Tyson is doing a segment on extrasolar planets. I'm only half listening, because I'm also trying to keep SteelyKid from trying to eat any of the furniture, but it's quite good.
All of a sudden, Emmy's head snaps up. "Hey!" she says. "He owes me a cookie!"
"What?" I ask. "Who owes you a cookie?"
"The human on the tv. He was just explaining science using dogs. Inferior dogs. That's my job!"
"Technically, it's my job. I'm the one who does all the writing, after all." I rewind the DVR a bit to…
rallain | July 18, 2009pre-reqs: vectors, kinematics
I haven't done a "basics" topic in quite some time. It's odd, I have used centripetal acceleration quite often, but I never derived the expression that I use. To get to the point, the magnitude of the acceleration of an object moving in a circle is:
Also, the direction of this acceleration vector is always towards the center of the circle the object is moving in. This is really not too difficult to derive (but it does use at least one "trick"). Let me start with an object moving in a circle at a constant speed. I am going to show to instances of the object…
rallain | July 18, 2009Note to self: don't do the mechanical equivalent of heat lab again. It doesn't really work that well and there are better labs to do.
So, what is the mechanical equivalent of heat lab? It is actually a pretty cool idea. Take and object and drop it. What happens to the kinetic energy the object had right before it hit the ground? Most of it goes into thermal energy of the object and surroundings. In this lab, the students measure the change in gravitational potential energy for a falling object (where object is really lead shot or something) and then measure the change in temperature in…
esiegel | July 17, 2009Understanding the Universe requires a lot more than just knowing some advanced mathematics, and even more than knowing how to apply that math. It requires a knowledge of natural history, and an understanding of the requirements for allowing that history to happen.
In other words, the laws of nature must be such that the Universe can exist as it does. Seems like a very simple, innocuous, and self-evident statement. Yet in this simplicity, we can learn a few important things about the Universe. Reasoning, using this statement, is often referred to as the anthropic principle.
There is more…
ejohnson | July 17, 2009
In 1964, Richard Feynman delivered a series of seven lectures to students at Cornell University on "The Character of Physical Law." Decades later, the video footage of the lectures was purchased by Bill Gates—who has said that Feynman could have inspired him to go into physics rather than software—and on Wednesday, Microsoft Research announced that the lectures will be made available on a specially-created website, along with commentary from other physicists, full transcripts of the lectures, and additional related content. The project, called Tuva after an area in Russia where Feynman hoped…
pontiff | July 16, 2009David Poulin sends me a job announcement for quantum information processing in the solid state at the University of Sherbrooke:
Permanent position for a Canada Excellence Research Chair (CERC) on solid state quantum information processing
University of Sherbrooke is seeking candidates for a Canada Excellence Research Chair (CERC). The successful candidate will obtain a permanent full professorship in the Physics Department of University of Sherbrooke in the Faculty of Sciences. The CERC program aims to attract and retain the world's most accomplished and promising minds. This program will…