From AP via National Geographic - click for original

Well, I bet they’re all that cute.
But I don’t care how big and manly you are, you know you’re moved to scritch it behind the ears and say “who’s a cute little kitty? That’s right, you’re a cute little kitty. Waschawhaschawhuh.”

From the original article at National Geographic.

June 29, 2009—The discovery of ten lynx kittens—including the young cat in this May 2009 picture—this spring marks the first time newborn lynx have been documented in Colorado since 2006, heartening biologists overseeing restoration of the mountain feline (lynx facts, map, and more).

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Need a class project?  Here’s one that could get you some cashola to boot.  Former physics teacher David Colarusso sponsors a contest for the best video to meld physics and film.  He particularly would like to see contributions from students and teachers!  If you’ve got some videos already posted on YouTube, just submit them here!  You can submit more than one.  The submission deadline is September 1, 2009.  If you need videos to show in your classroom, too, you can visit the site to browse their selection (and vote on your favorites).  There aren’t that many videos yet, so you’ve got a good chance.  The site needs some promotion, so spread the word.

Phylm contest website

Here is an excerpt from the contest rules:

Clips should contain one or more of the following:

• A critique/analysis of the physics presented in a fictional work. For example, could the bus in Speed have made “the jump,” or how strong would Spider-Man have to be to throw a car that far?
• An analysis of physics as revealed by the examination of a real-world video clip. For example, what forces does a gymnast experience during his routine?
• An explanation/presentation of some physics concept or theory. For example, what is the conservation of energy?

The clips should be aimed at a general audience of non-science majors. So please, no
calculus. Basic algebra and trigonometry are acceptable, however.

David Colarusso himself has a nice little playlist on YouTube on physics topics, mostly in E&M and modern physics.

And of course, if you can’t play YouTube videos in your classroom, check out my previous post on how to download videos to play offline.

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picture copyright Don Rathjen of Exploratorium

A pretty standard lab for introductory physics is to chart what constant speed (or constant acceleration) looks like, and graph it versus time.  There are all different ways to do this, but one is to use a ticker-tape timer, which I think is wonderfully cool.  The idea is to attach a piece of ticker tape to whatever object you want to graph the speed of, and then have some apparatus (a ticker tape timer) that makes marks on the ticker tape at regular time intervals.  If the ticker-tape timer made a mark every second (which would be convenient), then the distance between marks on the ticker tape would represent the distance traveled per second.  Generally they’re much faster, and timer speeds are measured in hertz.  Whatever the units, though, you now have a graphical representation of distance per time!

To make a graph, you can then cut up the ticker tape.  Choose a unit of time that you want to use on your x-axis — for example, 10 “hits” of the ticker tape timer.  That will be the unit of time.  (It’s generally arbitrary, since the timer doesn’t hit every second).  Chop your marked ticker-tape into 10-mark sections.  The horizontal axis, then, is time, and the vertical is distance per unit time.

If it was moving at constant acceleration, it will look like this:

If it sped up and then slowed down it will look like this:

All images are taken from the Practical Physics website, which has a lot of experiments using ticker-timers.  Go to their experiments website and search for “ticker” to see labs on measuring time, velocity, and other aspects of motion.

Of course, what is this “ticker timer” that will actually make the marks for you?  If you’re a tinkerer, there is a wonderful write-up for a DIY ticker timer from the Exploratorium (PDF) by Don Rathjen.  It’s a fussy thing to make, though, so really only for the type of person who reads those detailed instructions and thinks “Hey, I want to make that!” (and if you are, you’ll love Don’s instructions for making a clock escapement).  Still, I recommend downloading the instructions, because they give some really cool examples of how you can use these, including how to make displacement and acceleration graphs (instead of just velocity graphs) and how to measure “g”.

If you have the money, though, Arbor does sell (for $140) a spark timer that does the same thing.  Here is their ticker-timer lab (written for advanced and introductory levels) with links to all the needed materials.

Useful for all sorts of things, they also sell cheap constant acceleration cars and constant velocity cars.  (New, improved!  It actually goes straight!).

And, if you really need it to be on the cheap, there are some online applets for constant velocity and constant acceleration that were recommended by a physics teacher.

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A good little post by Derek Bruff recently details his arguments why clickers are useful in college classrooms.  If you’re a skeptic, or trying to convince a skeptic, it’s worth checking out his post

We’ve also got a video that shows many of these same points — here that is.

Once again, here are a few very useful books on using clickers in the classroom:

Peer Instruction is the “bible” of clicker usage, including sample questions in physics. This text will change the way you teach! Derek Bruff’s new book Teaching with Classroom Response Systems comes highly recommended by Eric Mazur himself, which is high praise! Doug Duncan’s Clickers in the Classroom is a short and pithy gold standard of how to use Peer Instruction in the classroom.

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I’m giving a workshop on the use of clickers in K12 classrooms next week.  I need your help!  The research says that teachers focus too much on the surface features of “example” questions that you give them.  If they’re a science teacher, they tune out during a literature question.  If they’re a history teacher, the science question doesn’t mean anything to them.  They can’t abstract out the central features of that question to see how it might relate to their subject.

So, I want to come up with a question (or two) that are not specific to any discipline.  I need a multiple choice question, that’s hard to answer and requires discussion with your neighbors, and would interest any average American adult.  I was thinking something with nutrition or health…. or maybe something puzzle-like, like the Monty Hall problem (though that’s a little mathy).  My colleague has a nice question about “how many liters of Scotch are stored in Scotland” which you actually *can* answer by making a few estimations — but I kind of like the idea of using a question that has a right answer, since that more matches how teachers would use it in the classroom.

I could also use some examples of good clicker questions from non-science areas, and any K12 question banks that people have.

Thanks!

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Wow, check out this beautiful video of visualizing fluid flow with a special tracer fluid (courtesy of Sebastien at the Exploratorium).  Stunning!

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I guess that I’m the last person to see this, but this YouTube video on digital technology and college education from Kansas State University made the rounds a while back.  It’s a very moving presentation of how distanced students feel from their own learning and the role that technology plays in that.

From a teacher’s perspective, there are some things that you can do to keep students on task and engaged in the classroom (and make that lecture more relevant to them).

On that note, I went to a nice presentation by Diane Sieber on “Facing Facebook” recently, talking about the challenges facing college instructors with the digital age.  How do you work with the technology instead of fighting it?

The results of a Pew research study in 2006 showed that, in class

• 80% of students access Facebook or MySpace
• 73% text message, IM or email
• 90% browse the web
• 45% read news or blogs
• 25% take notes
• 18% play online games

One thing that she does is to avoid Powerpoint at all costs.  Powerpoint just sucks the energy out of a room, she says, and students take it as a cue to tune out.  Powerpoint reduces complex ideas to simple slides, or at least students see them as reductive.  It also makes lecture scripted and linear — everything is in order and there is this “forced march” through the materials.  This kills any sense  that there’s a risk to not paying attention.  You might as well check your email and then download the powerpoints later.   She uses Mind Manager Pro to create a concept map of her lecture.

She didn’t encourage banning laptops, since that penalizes students.  Help students use their technology more productively, she says. There are some dirty rotten tricks, like using a “dummy” wireless router to draw wireless traffic from the main campus router to that non-internet connected router. You can also restrict laptops to the front row of class, but I’ve seen students still off-task with that method.

But more productively, she has the class create a social contract using an online wiki.  She uses the wiki throughout class, and the social contract is the first thing they do.  Then the whole class has bought in to the contract and enforces it.  That contract always ends up including something about the use of technology in the classroom.  After all, it’s distracting to other students if the student in front of them is surfing the net.

Just being aware, as an instructor, when people are looking at the screen and not touching the keyboard, can help.  Call students by name to draw their attention.  Walk around the class, beyond the first five rows.  Have “tops down” time when screens have to be down, signalling that this is an important topic, and breaking up the pace of class.  She even ran some performance correlations, showing that those students with laptops open during class had lower grades on the test –this was very surprising to students, and they changed their behavior.

These media can complement class activity, too, by assigning a student to googlejockey during class, or using tools such as ubiquitous presenter.

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From Nessman on Flickr

Here was an interesting discussion on a science teacher’s listserv, which came down to the question — can a vacuum become a conductor?  What is it that we really need in order for charge to flow between two points?  What is the physics of electron flow?  The physics teacher in question wrote:

The Paul Hewitt book has a test question that reads:  In order for charge to flow from one place to another, there must be a
A. Potential difference between the two places.
B. Conductor, such as a wire, connecting the two places.
C. both A and B.
D. none of these.

The book’s answer is C (both A and B).  I’m wondering why A isn’t the answer. In the case of the van de Graff or lightening you create a potential difference between two locations (say me and the van de Graff) and the charge will eventually flow … I guess the air acts as the conductor from van de Graff to me? But is there a situation where there is enough of a potential difference between to places and charge doesn’t flow? Would the van de Graff not work in a vacuum?

A veteran physics teacher (Al Sefl, who always knows more physics than moi) responded:

The key to the Hewlett question is that it asks about charge flow.  Current cannot flow through an insulator until the point of breakdown is reached.  If you have a sphere X with a positive charge and a sphere Y with a negative charge there will be no flow between them until a conductor connects them.  Before that conductor is there, there will be lines of electrostatic force but no flow.  If the potential were great enough the air would break down to become a conductor and you would have flow.  So, C is the correct answer, you must have a potential difference AND a conductor to conduct the charges.

Yes, a Van de Graaff generator will work in a vacuum.  High voltage capacitors used in broadcast transmitters and radar units are vacuum capacitors where the charge is stored between two plates surrounded by an evacuated space.  The electrostatic lines of force do not need air to exist.

That’s all fine and dandy, but most of the people on the listserv didn’t understand that second paragraph (and neither did I), not knowing enough about broadcast transmitters and such.  A teacher asked, do you mean that the Van de Graaff will store charge in a vacuum, but not throw off sparks?  After all, what would the charge be flowing through if the Van de Graaff is in a vacuum?  There’s no air to ionize (or “break down”).

Al responded with a clarification:

A vacuum may also be a conductor.  The old cathode ray tube of years past sends a beam of electrons from a gun through a high vacuum to impact the phosphor screen.  So, when the potential becomes high enough current will flow through a vacuum.  In a CRT it does get an assist from thermionic emission in the gun.

The miniature lightning bolts we see from a Van de Graaff are really the paths of broken down insulator air that has become conductive and ionized.  You would not see that in a vacuum.  If you put a sharp point on the negative terminal then the charge concentration will push off electrons that will travel to the positive terminal.  The vacuum will become a conductor.

So, C is still the correct answer.  If charges FLOW they must do so through a conductor.  ANYTHING will become a conductor if the electrostatic charge exceeds its dielectric.  If electrons are flowing through something it *is* a conductor.

Perhaps where the Hewlett presentation becomes unclear is the definition of what a conductor is.  Most of us immediately think of a piece of copper wire *but* it can be anything if the potential is high enough.

So, a vacuum can become a conductor, even though there’s nothing to ionize (and thus you won’t see the glow from the electrons as they travel through a vacuum, as you do in the air).  But by definition, if charge is flowing, it’s flowing through a conductor!  Paul Doherty explained that when there is an electric field that is large enough (it has to be very very large), then it will produce electron/positron pairs in the vacuum.  Those electrons and positrons are what flow to conduct electric current.

On a side note — the charged particles given off by the Sun aren’t visible as they pass through the vacuum of space… but they are visible when they hit our magnetosphere as the aurora borealis.

And another teacher offered a clarifying comment:

I was taught to get over the idea of being protected by an insulator. We were told that an insulator is a bad conductor. My trade teacher felt that insulator was a weak word and preferred to talk about everything being a conductor, just good conductors (copper) or bad conductors (glass).

So, the discussion got interestingly esoteric here.  The original questioner then posited:

If any space can be considered a conductor given a high enough potential difference, then I think the answer to Hewett’s question should be we just need a potential difference to get a flow of charge.  After all, he didn’t explicitly state that we need to have charged particles, which I think would be necessary to have a flow of charge.  So why state that an omnipresent conductor is necessary?

Also, if a vacuum has charged particles moving through it, is it still a vacuum?

Paul Doherty emphasized that the correct answer to the question is still “C.”  You can have a potential difference and no flow of charge, because the voltage may not be low enough to create its own conductor out of the insulator between the two places.  With enough potential difference an insulator is turned into a conductor, but you STILL need both a potential difference and a conductor for charge to flow.

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I came across a new science blog recently – A Schooner of Science — and really enjoyed Sarah’s fresh and funny writing style about all sorts of things that this blog doesn’t tend to cover — namely, biology and chemistry.  (I write about them when I can, but, well, it does all come down to physics, after all, right?  Right?).

Sarah cheerfully agreed to cross-post one of her recent articles in lemmings (yay lemmings!) and whether it’s really true that lemmings throw themselves off cliffs to reduce their population.  Enjoy, and check out a Schooner for more stuff (most recent posts — 5 most remarkable animal penises!).

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Nothing like going retro and playing a game or fifty of LEMMINGS!!! I squandered many an evening in my youth curled over a computer screen, thinking of ways to keep those suicidal wanderers alive while they walked carelessly towards cliffs.

Some of the levels were so bizzarro I’d wonder “how did they get themselves INTO this mess? Do they WANT to die? Cute little green-haired munchkins!” For fun, here’s a real lemming – still cute but in a more hamsterish way:

At some point I was introduced to the idea that yes, lemmings DID want to die because of a brilliant population-control technique ingrained in their DNA. I’ve had many a teacher who have lamented the human desire to be fruitful and mulitply, crying that we were destroying the planet out of sheer numbers. Whether we would continue to survive would depend on whether we realised that space was running out and slowed down… otherwise we’d bang ourselves straight into extinction. Are we an r-selected species, or a K-selected species, is our growth rate exponential, or are we just midway up an S-curve? Whenever I read that the suicide rate was increasing, I would think to myself – maybe we ARE like the lemmings. Maybe this is all some genetic grand-scheme to thin out our numbers.
I don’t think that anymore, doesn’t it sound a bit ridiculous that you can have so many animals around that they disappear? It sounds a bit like Jimbo Kern from Southpark – “We’ve got to kill more animals so they won’t die!”
And the lemming thing – it’s all a LIE!!! Those lemmings didn’t kill themselves. The poor little rodents were chased off a cliff for a Disney movie. This Disney movie in fact, White Wilderness.

Hell, these lemmings weren’t even migrating and accidentally fell into the sea, or thought there was something worth swimming to on the other side of the ocean. Nope, they were pushed off the edge by film makers just to get the right shot. Lemmings aren’t even native to Alberta, Canada, where the footage was taken – they bought them from Inuit kids! So consider this myth debunked. It wouldn’t be the last time television pushed animals into killing themselves either – consider Happy Tree Friends.

If you want to play the game again and relive the lemmings good times, do it here Love the hair.

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Originally posted on a Schooner of Science here.  See more of the Captain’s scientific musings over on her Schooner.

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I’ve had a set of “bad science movies” on my Netflix queue for a while, and every once in a while I dip into it.  Each time it feels a bit risky, like trying some weird new combination, like cherry dip on my mint chocolate chip ice cream cone.  Sometimes it’s OK.  Sometimes it’s not the best use of my money, so I cut my losses and go surf the internet.  But this time, it all worked out, it all worked out great. On the other hand, my brain was rather fried from a long day slogging through snow covered peaks (see picture below). 

Climbing Mt. Neva. Photo by Brian Moore.

So, after a day like this, this kind of dumb was just what I wanted. Of course I knew that the whole premise of “The Core” would be laughingly stupid.  (The earth’s magnetic field has stopped!  We have to drill down to the center of the earth and jump-start it!).  But, even allowing for the whole “flawed premise” (after all, being a writer is about being creative, so we can cut them some slack to create the storyline, I guess).

But I was still giggling here and there.  Even simple stuff — the pigeons go beserk and start crashing through storefront windows (c’mon, birds fly into windows all the time and don’t smash them to smithereens), was just silly.  And while the movie writers were careful to provide at least pseudoscientific explanations of how most things worked, I guess they knew that it was going to be beyond their ability to come up with a decent explanation of how Mission Control could manage to communicate (instantaneously!) with the ship as it burrowed through hundreds of miles of molten metal.  So they didn’t even try.

But I needn’t bother to spend the time to roast this movie in the pan that it so richly deserves, it’s been done far beyond my ability on Intuitor’s Insultingly Stupid Movie Physics.  (They have a bunch of other wonderful reviews of popular movies).

Here’s a zinger from that site:

Keyes proceeds to demonstrate the effects of losing the magnetic field by lighting the aerosol from a can of hair spray and flaming a peach representing Earth. He makes his explanation simplistic since he’s talking to military brass who can’t grasp complexity, even though they lead one of the most complex and high tech organizations in the world.

Whether Earth did or didn’t have a magnetic field would make no difference….

Not only does Keyes not know the difference between forces and energy but he apparently believes that electromagnetic radiation such as microwaves can be deflected by a magnetic field. Here’s a quick experiment, try using a magnet to deflect the electromagnetic (EM) radiation emitted by a flashlight. The EM radiation is a beam of visible light and, although we hate to spoil the experiment, nothing will happen.

Whether Earth did or didn’t have a magnetic field would make no difference as far as microwave radiation is concerned. First, the magnetic field doesn’t affect it, and second, there’s very little of it in the first place. The Sun emits lots of electromagnetic radiation but most of it is visible light. It sends very little microwave radiation. At its worst, the Sun’s microwave radiation can cause interference with radio or cellphone transmissions but poses no significant health hazard.

Ouch.  Of course, the plot also has plenty of loopholes, scientific or not:

The cast is rounded out by DJ Qualls who plays a stereotypical convicted computer hacker called Rat. He is brought on board for the critical task of preventing anyone on the Internet from precipitating a worldwide panic by posting theories about the impending disaster. Apparently, dead pacemaker patients, berserk window-smashing pigeons, bizarre space shuttle crash landings, monstrously powerful thunderstorms, the Golden Gate bridge collapse, unexpected nightly displays of the aurora borealis, and the total destruction of Rome, all in around three months, aren’t enough to generate concern.

Besides, no TV, newspaper or radio news organization would ever speculate on such matters, let alone ask reporters or high-priced consultants to find answers. No televangelist would see anything Biblical in these signs of impending judgment nor would any private citizen be panicked without input from a webpage.

Bottom line:  rent “The Core.”  Go, do it now.  If you’re a science teacher, assign your students to watch it, and then come up with 5 examples of “what’s wrong with this picture.”  What a fun assignment.

Incidentally, I got much of my list of bad (and good) science movies from Sidney Perkowitz’s Hollywood Science book, which reviews early to recent movies and explains the good, bad, and ugly in the science in these films.  It also has a list of the all-time best (and the all-time worst) science movies.  Worth a look.

One good outcome of this movie (which really is a hoot, and not a terrible movie if you like this sort of thing, which I do), is that it was purportedly the impetus to start the Science and Entertainment Exchange (run partly by Cocktail Party Physics blogger Jennifer Ouellette), which connects scientists with the folks in the entertainment industry so that stuff like this won’t happen again.  They have a blog too.

You can also see Blick on Flicks at the National Science Teachers Association for some more blogging on movie science (and how to use it in your classroom).

I am a science education and communications consultant -- view my website for my full range of services.