January 16, 2009
Poking around on the internet looking for interesting problems to assign the students I'm about to have this semester, I came across this one:
How much energy must a 450 kg cow expend in jumping over the moon?
Fig. 1: Buzz Cowdrin?
Now hints and solutions are available on the linked site, so what…
January 15, 2009
Doing a lot of driving this week, and since the interstates I'm driving (I-49 and I-10) are deathly boring, I have a lot of time to think. Being a physics nerd, I do a lot of thinking about physics. This trip the physics thing I'm thinking about is tire pressure.
Fig 1. A car. From the Wikipedia…
January 14, 2009
Astrology has never so far as I know proposed a scientific mechanism by which the planets should affect the lives of us mortals. I suppose this is fair enough, you wouldn't expect magic to work by normal laws. If the position of Jupiter says you should spend the rest of the week face down in the…
January 13, 2009
I hope this doesn't count as biting the hand that feeds, but hey, dissent is supposed to be the highest form of patriotism or something. From my university:
COLLEGE STATION -- The chancellor of the Texas A&M University System wants to give bonuses worth up to $10,000 to some instructors, but…
January 12, 2009
Whew! ScienceBlogs is back up. Mostly. There's been some kinks, but so far things are mostly working. No LaTeX yet, but I'm agitating for it vigorously. Especially for the comments. The ability to work with equations is something that no self-respecting science blog should be without. I'm…
January 9, 2009
As you've probably heard, ScienceBlogs is going to be silent for a day or two starting... 1pm today I think? I'm not sure, I don't pay attention very well at our board meetings. And by board meetings I mean whatever happens to get posted on the internal message board. But apparently we're…
January 8, 2009
This one's a little of the beaten path for this site, since it's not physics or even anything I normally follow as a hobby. But along with science and many other things I'm a bit of a firearms enthusiast, and since guns are closely connected with hunting it probably wasn't unlikely that I'd come…
January 7, 2009
Reader Scott writes in with a good question that I've heard posed by several people in various places, because it really goes to the core of the counterintuitive nature of relativity.
Okay, let's assume I'm in a spacecraft moving at a speed of c-1 m/s. That's one m/s less than the speed of light.…
January 6, 2009
Over at Uncertain Principles, Chad is talking football. There's this pesky problem of spotting the ball at the end of the play. In a game where fractions of an inch can make or break the end result, too often the issue is determined by a more or less random guess by the referee of where the ball…
January 5, 2009
I was out of town (again) this past weekend, hence the posting shortage. Why in the world is it so much harder to find time to post during a nominal between-semester-break? I dunno, but it seems to be true. Free time doesn't scale the way you'd like.
One of the fundamental skill sets a physicist…
January 2, 2009
The Constant Fire: Beyond the Science vs. Religion DebateAdam Frank
Adam Frank is an astrophysicist and a man on a mission. It's a brave mission, one which cuts strongly against the grain of the science vs. religion zeitgeist. It's probably a mission which won't succeed.
Beyond the Science vs.…
January 1, 2009
Real-life physics can be a pain.
New Year's Eve I went with an old high school friend of mine to meet some people and shoot fireworks. This concluded at a little before one in the morning, and after that we left. We wanted to catch up on what had been happening some more and so we drove around…
December 31, 2008
When I was a kid my younger sister used to play basketball in a city league and my family would go watch. The game clock would reach the final seconds of each period and the kids in the stands would count down. 3! 2! 1! Zero!
The clocks were such that with less than one minute remaining, the…
December 30, 2008
Apropos of the calorie/Calorie discussion yesterday, here's something interesting to think about with regard to the energy used in exercise.
The formula for gravitational potential energy is m*g*h, where m is mass, g is the acceleration due to gravity, and h is the height. Of course this is if the…
December 29, 2008
Over this past semester I've discovered something unfortunate. If a person doesn't get much exercise, snacks when bored, and shops when hungry, that person will tend to gain weight. That person is of course me, and so I'm going to try to do something about it. It's by no means a new year's…
December 28, 2008
Here's this week's Sunday Function. In the universe of functions it's an utterly typical suburban middle class citizen, with a pleasant but quite ordinary job in a downtown cubicle farm for Physics Incorporated.
His name is.
In a little more detail, you'll notice that this function is the product…
December 27, 2008
Great! So did I!
Now the sky is a big place, and telescopes don't often come with an astronomer to explain how to use them. I'm not an astronomer either, but I've been an amateur stargazer on and off for years and I might be able to give you some good advice.
First, the telescope itself. There's…
December 25, 2008
On this, my first 25th of December here on ScienceBlogs, I'd like to wish you and all your family and loved ones a happy, merry, and joyful Christmas. In honor of the occasion, my favorite Christmas song:
O Holy Night
O holy night! The stars are brightly shining,
It is the night of our dear…
December 16, 2008
Greatest Physicists #1 - Isaac Newton
The first and greatest physicist in my estimation is Isaac Newton, born in 1643. Lots of commenters absolutely correctly picked out Newton for the top spot, and had I picked anyone else (with the just barely plausible alternatives of Einstein or Galileo (and…
December 15, 2008
#2 - Albert Einstein
Einstein. When a person's name and photograph are both literal synonyms for genius, it's a pretty good sign they're among the greatest of the greats. But even if Einstein had not become the popular legend which lives on to this day, he'd still tower above the science of…
December 14, 2008
The Exponential Function. I think this is the first time we've done it here. It won't be the last. You could write a book about it, and someone probably has. Here's the usual picture:
This graph isn't as pretty as the usual, because I'm at home with my old copy of Mathematica 5 instead of the…
December 13, 2008
I dislike the remake of The Day The Earth Stood Still, and I haven't even seen it. Not for the usual reasons - for instance, I think Keanu Reeves is a good actor when used in the right roles, and "space alien" is certainly one of those roles. I dislike the premise. Some alien species comes down…
December 12, 2008
From the inimitable xkcd, a comic about relativity in sex:
This rather clever piece of humor is referring to the relativity of simultaneity. According to relativity, time and space are different for observers in different reference frames. Events which are simultaneous in one frame are not…
December 11, 2008
So Tony Soprano pitches ties a concrete block to Salvatore Bonpensiero and pitches him into the ocean, where he will inform the police no more. Being a big guy, Bonpensiero has a fairly low density compared to your average human being - say, 0.96 grams per cubic centimeter. That's less than water…
December 10, 2008
A mysterious gap in posting? Must be finals time! As of now I'm done. We'll see how they went. One of them went well for sure, the other sort of depends. My own students are having their own exams as well, and I've got my fingers crossed for them.
One of the things that's going to be on the…
December 7, 2008
This rather striking image is the imaginary part of the Airy function. Rather than a lot of words today, I'd like to just present this mathematical function as art.
I've always disagreed with Whitman in his assessment of science, but it is nonetheless a good thing to occasionally look up in…
December 6, 2008
Yesterday I posed a famous trick question, and we had the shortcut answer, the long "standard" answer, and a particularly elegant solution by commenter meichenl. Turns out he has his own blog called Arcsecond, and it's really fantastic. He focuses mostly on examining interesting mathematical…
December 5, 2008
Challenge question! It's either very easy or somewhat difficult depending on how clever you are at approaching it. No fair answering if you've already seen the problem before, though if no one's managed it in a few hours I'd say it's fair game to post the solution if you already know it.
Two…
December 4, 2008
Seed's editorial policy is unusually generous in the latitude we ScienceBloggers get. Let's hope it's generous enough for this!
Linked via Instapundit, I saw this interesting article about theft of and damage to speed cameras. As an strong supporter of civil liberties, this warms my heart. If a…
December 3, 2008
Before the physics, I want to point out one of the most interesting ScienceBlogs posts I've seen in a long time: Not Exactly Rocket Science discussing the body-swapping illusion. You should read it.
Now, here's a quiz I gave my Physics 201 students. Easy as usual, but I'm a sucker for these order…
