Physics
drorzel | November 24, 2009The official release date for How to Teach Physics to Your Dog is exactly four weeks from today. So here's a dramatic reading of Chapter 3 to mark the occasion:
I've put this up before, but I edited it to remove the URL, which was apparently a deal-breaker for booksellers. And yes, I will post about something other than the book, Real Soon Now...
rallain | November 23, 2009Everyone knows, or should know how much I like MythBusters. Here is the problem. Below is a picture of Adam analyzing the motion of a an exploding water heater.
Actually, I applaud Adam for his creative use of the vernier caliper. Really, it is an example of "making things work". However, in this case there is a very nice alternative - Tracker Video Analysis. So, here is what I am going to do. This will be a short tutorial on using Tracker. I will use the same video from the episode of the exploding water heater. The goal - how fast and how high did the water heater go. Or as the…
esiegel | November 23, 2009The cradle rocks above an abyss, and common sense tells us that our existence is but a brief crack of light between two eternities of darkness. -Vladimir Nabokov
Last Friday, I posed a question to you, and you kindly responded by voting as to whether, when you crossed the event horizon of a black hole, the lights would stay on or go off. The results so far?
What do I have to say? Good for you! Just because no light gets out doesn't mean that you can't see the light that comes in! When you're in your spaceship, very few things matter.
You could be in a strong gravitational field, like exists…
drorzel | November 22, 2009Look! How to Teach Physics to Your Dog is a real book:
Emmy says, very seriously, "You will buy a copy, won't you?"
Of course, like everything else in this house, SteelyKid had to grab a copy:
She whipped through to the last page pretty fast:
Emmy says "What'd you think, human puppy?"
SteelyKid says "If I knew how to read, Daddy's book would be my favorite book ever. People who can read should definitely buy it."
You heard the kid and the dog...
esiegel | November 20, 2009Black holes have come up a couple of times this week, and I've always wondered something. When you fall into a black hole, all sorts of strange things happen.
The most well-known one is that nothing -- not even light -- can ever escape once it falls in. Well, my question is, if you fell in to a black hole, as you crossed the event horizon in your sturdy, well-lit spaceship, would the lights stay on or would they go out as you crossed into the black hole? (Ignoring the tidal forces that would rip you and the spaceship apart.)
In other words, you've read the first 1497 pages of the Count of…
esiegel | November 20, 2009Why it is that of all the billions and billions of strange objects in the Cosmos -- novas, quasars, pulsars, black holes -- you are beyond doubt the strangest? -Walker Percy
When you watch someone fall into a black hole, what you actually see is pretty surprising. You see, a black hole's gravity distorts the space around it, and it does so without providing any light of its own, giving you a unique perspective on the Universe.
Well, if you watch someone else fall in, you'd see them approach the black hole normally, and then the bizarreness starts. As they go deeper and deeper into the…
rallain | November 20, 2009In my previous post on launching a pumpkin (punkin chunkin) I essentially just looked at what happens to the pumpkin after it is launched. How fast would you have to shoot it to go 1 mile? The answer seems to be around 1000 mph and they are currently shooting them around 600 mph.
The question for this post, how fast can you launch a pumpkin so that it does not smash into smithereens? First, why would it smash at all? Here is a diagram of a pumpkin being launched while still in the tube.
The pumpkin launcher works by releasing compressed air inside the tube. This means that the force…
rallain | November 19, 2009Last night I saw the newest episode of MythBusters. One of the myths they revisited was the exploding water heater. Well, it turns out that I had an analysis of this first explosion, but I didn't move it over when I switched software. So, here it is.
In case you never saw the first episode of exploding water heaters, here is the important part:
If you are impatient, here are the answers (from the video analysis):
Time of flight = 11.8 seconds
Max height = 167 meters = 548 feet
Launch speed = 234 mph
Speed on impact with the ground = 76 mph
First, from re-watching the video, I can see (…
drorzel | November 19, 2009It's not often that I regret having a cell phone that is just a phone, but this is one of those occasions-- I stopped by my publisher today to talk about marketing and publicity, and record a video for the web, and got a stack of finished copies of the book, hot off the presses. If I had a cell phone camera, I'd post a picture, but I don't, so you'll have to settle for a plain-text "Woo-hoo!"
On an only vaguely related note, our cultural activities in NYC will include some college hoops, as there's a preseason "tournament" taking place at Madison Square garden tonight. Syracuse vs. Cal, and…
esiegel | November 18, 2009In the comments on one of my posts, someone pointed me towards Stephen Crothers, who gives the following argument (in a nutshell) as to why black holes cannot possibly exist:
General Relativity is our theory of gravity, which relates the curvature of space to the gravitational acceleration of objects.
This theory only works in certain regimes; it breaks down at the point of singularities.
A black hole, as predicted by Schwarzschild, is a singularity.
Therefore, since singularities are forbidden by General Relativity, there is no reason to think that black holes exist.
(You can watch his…
drorzel | November 17, 2009As every physics-loving dog knows, the idea that electrons behave like waves was first suggested by Loius Victor Pierre Raymond de Broglie (the 7th duc de Broglie) in 1923. The proper pronunciation of his surname is a mystery even to human physicists, though. So, how would you say it?
Louis Victor Pierre Raymond de Broglie's surname is pronounced:(polls)
Even though Louis was a quantum pioneer, please choose only one of the available options.
drorzel | November 17, 2009Sunday night, the Patriots lost a heartbreaker to the Colts 35-34. The talk of the sports world yesterday was Bill Belichick's decision to go for it on fouth-and-two on his own 28 yard line when he was up by six with just over two minutes to play. They didn't get the first down, and turned the ball back over to the Colts, who went on to score a touchdown and win the game.
Yesterday's discussion was a low point even by the standards of sports talk radio, with one idiot after another holding forth about how stupid Belichick's decisions was, and how he "disrespected his defense," and various…
drorzel | November 17, 2009There's been an independent rediscovery of the notion of using dogs to explain physics, as you can see in this YouTube video of Golden Retrievers explaining the structure of atoms:
Emmy thinks she should get royalties, in the form of cheese. But then, she thinks that about everything...
esiegel | November 13, 2009Can you touch your toes? Seems like an easy thing to do for those of us who have the flexibility.
Now, here's the challenge. Stand with your back and your heels pressed up against a wall, and now try to touch your toes.
You can't do it! Not without putting your hands down on the floor, you can't. There's a super-simple reason for this: center-of-mass.
For human beings, your center-of-mass is somewhere in your abdomen. It's lower down for women than men, but in the abdomen region for everyone. When you typically bend down to touch your toes, you'll notice that the upper part of your body…
rallain | November 13, 2009Not really. Here are the details (and some data) for the Millikan Oil Drop Experiment without the oil drop that I talked about previously (originally from The Physics Teacher - lucky you, it was a featured article so it should still be available (pdf)).
The basic idea that Lowell McCann and Earl Blodgett from U of Wisconsin propose is to do an experiment similar to the oil drop experiment, but not so squinty (if you have done the oil drop experiment, you know what I mean). Instead of dropping charged oil in an electric field, they drop containers with metal nuts in water. The goal is to…
rallain | November 10, 2009This is for commenter JimP. How do you take into account uncertainty when using video analysis? A great question. The first thing to think about is where does the uncertainty come from? My first guess would that it would be from the user. Where does the user click? Is it right on the object in each frame? Is the scale set correctly? I guess there could be other sources of error - maybe there are repeating frames that are a result of encoding. Maybe there is interlaced video frames.
Well, what to do? I will just look at one motion in particular and do the analysis several times. I…
drorzel | November 6, 2009Today's Quantum Optics lecture is about quantum computing experiments, and how different types of systems stack up. Quantum computing, as you probably know if you're reading this blog, is based on building a computer whose "bits" can not only take on "0" and "1" states, but arbitrary superpositions of "0" and "1". Such a computer would be able to out-perform any classical computer on certain types of problems, and would open the exciting possibility of a windows installation that is both working and hung up at the same time.
There are roughly as many types of proposed quantum computers as…
rallain | November 5, 2009Very simply, parallax is an apparent motion of an object due to a change in observation position. Let me start with an example. Here are two photos. I took a picture of the cabinet in the background from two slightly different positions. In the foreground is a clone trooper that did not actually move.
I added the dotted line so you could see how the clone trooper appeared to change positions with respect to the background. Here is a diagram of the camera in the two positions along with the toy.
Since the camera changed positions, the object that is closer appears to have moved with…
drorzel | November 5, 2009It's not getting as much press as the "X Prize" for private rocket launches, but NASA has quietly been running a contest for work toward a "space elevator," offering up to $2 million for a scheme to transmit power to a small robot climbing a 1km cable. Yesterday, the team from LaserMotive, including certified rocket scientist and friend of the blog Jordin Kare, successfully powered a robot up a 900m cable using diode laser arrays to send power to solar panels on the robot. They managed an average speed of 3.73 m/s, which doesn't get them the full $2 million prize, but qualified them for the $…
rallain | November 4, 2009I already attacked the 2008 Punkin Chunkin Show. So, now I going to give the chunkers some tips. In case you aren't familiar, the Punkin Chunkin contest has teams create devices to launch a pumpkin. They have different categories, but I am going to focus on the air-powered devices. The basic idea is to make an over sized pneumatic potato gun. Here are the things I was inspired to think about.
It seems all the canons were aimed at about the same angle. Did they guess at the angle? Or is this trial and error? What would be the best angle for a pumpkin launch?
Does the optimal angle of…