Hail storm in Sacramento at 240 fps

We had a pretty heavy downpour of hail at about 5:45 pm on Wednesday, March 23. I grabbed my Casio EX-FH100 and set it to 240 frames per second. From the safety of my eave, I shot a few clips. Pea-sized hail poured down and thunder rolled through. (Always best to go full-screen on these, in my humble opinion.)



I liked the bouncing action apparent near the gutter.



The hail lasted much longer than it usually does (in my experience). So the accumulation was somewhat significant by the end of it all.



These are unedited and may run longer than your patience. If so, skip to the next one or just click pause to stop. Enjoy!

XKCD radiation dose chart

You'll find news and comment on the nuclear plant situation else on the interwebs.

All I can do is opine that we will very likely need to increase our reliance on nuclear power generation in the future, so we very much need to get it right and pay particular attention to details. Low-bidding and shoddy construction at a coal plant can have bad consequences. The same at a nuclear plant can be widespread devastation. The consequences are too severe for us to be anything less than brilliant on design and construction.

Anyway, in our efforts to Know Nukes, XKCD has prepared a nice chart. Worthy of printing on whatever large-format printer you have access to. It makes a graphical display of radiation doses from natural background up to lethal.

And West-coasters, it's still safe to play outside.

XKCD Radiation Chart

Brainiacs electric fence redux

Last year I posted a note about a groovy clip from the now-defunct British science show, Brainiac: Science Abuse (Brainiacs for short). I learnt (I mean learned) that one of the featured circuits was, in essence, an R-2R resistor ladder: a design used in digital to analog conversions.

When I showed the clip to this year's classes, I was compelled to stop the video at specific points and pose questions to encourage predictions and discussions. My inner teacher at work once again.

I've now chopped the original clip up and worked it into a presentation so I could add questions and illustrations where appropriate.

I also developed a brief student worksheet to accompany the video demo. It's what I like to do.

The zipped QuickTime of the preso is kinda hefty (the embedded video bulks it up to nearly 400 MB). And as with all my interactive QuickTimes, it won't stream. You need to download it, unzip it, and run it. But only if you want to!

I think it's worth the time. Your mileage may vary.

Electric Fence zipped interactive QuickTime (huge-normous)

Electric Fence student demo question worksheet (not so big)

Closed course—professional driver

Barrel-rolling a sports car inside a freeway tunnel isn't everybody's idea of fun. But apparently these Mercedes-Benz guys had nothing better to do.



Thanks to Brad Huff for sharing this gem.

UPDATE: Wired's dot.physics has a nice analysis of the physics.

More posters to promote physics enrollment

Real estate agents say the three most important characteristics of a property are "location, location, location." Advertisers live by a similar rule, and that is "frequency." Potential customers don't really hear/see your message until the seventh time they've been exposed to it.

So if you're looking to promote enrollment in high school physics, I encourage you to make liberal use of the TAKE PHYSICS posters. Better yet, come up with your own; they'll likely be better than mine. (Unless you live way out on the cutting edge, though, I don't recommend designing a physics version of the old 'Expose Yourself to Art' campaign. Just throwing that out there. But if you do, please send me a copy!)

The American Association of Physics Teachers (AAPT) has designed a couple of nice posters and includes links to them on their Resources page.

One is "The Top 10 Reasons Why You Should Take Physics."

Another is "Seven Myths About High School Physics." OK, technically, that one is a brochure. But print its two sides big, connect them, and you've got a hugenormous poster.

I recommend downloading high-resolution versions of these and printing them to the biggest paper you can handle. I have an Epson 3880 (because I'm into photography), so I can print to 17" x 22" paper. Your school might have something capable of more than that.

Print them and post them. Be aware of the high-traffic areas at your school. Think like an advertiser! Get them out into locations where they'll be seen. Don't relegate them to the window of your own classroom. That's not where your market is! Be sure to post them in the guidance counselors' office, where students are often waiting around for their appointment. There they are, with nothing to do but sit around and read the posters on the wall.

One might reasonably wonder if advertising is the way to go. Does it make your program appear desperate? No one else is advertising, why are you? (See next article.) If you are happy with your enrollments as they are or are uncomfortable stepping on the toes that might be stepped on by your campaign (again, see the article below), advertising is not for you.

If you know of a better means to higher physics enrollments, please share your ideas in the comments. I will say that my own early efforts—making presentations to the chemistry classes and even mounting a sophisticated, "Ed McMahon-style" personalized direct mail appeal—had nowhere near the efficacy of my much simpler TAKE PHYSICS campaign.

Damn the torpedoes: full speed ahead!

A question about my "TAKE PHYSICS" posters recently came up on the Advanced Placement Physics Electronic Discussion Group (EDG).

(The AP Physics EDG is an old-fashioned messaging system reminiscent of Listservs. Informative and engaging, but a ploddingly slow throwback to the mid-nineties in comparison to modern fora such as those run via vBulletin and the like.)

A physics teacher had posted the TAKE PHYSICS posters on campus but was met with a volley of disapproval from colleagues in his department. To preserve harmony, he took the posters down.

I went through this turmoil years ago; it's something of a birthing process. Presenting the posters without describing potential pitfalls could be seen as reckless or irresponsible on my part. So let me post a FAQ. (If the '90s nostalgia gets any thicker, we'll need to crank up some Toad The Wet Sprocket or Gin Blossoms hits for background music.)

Why Advertise A High School Science Class?

Physics has traditionally been marginalized in the high school science sequence. Everyone takes biology. Half of biology students take chemistry. And whoever's still up for it? They take physics. That's a pipeline to disaster as far as I'm concerned. Many of the students at my school go on to college; it seemed to me that all of them on that path should have a year of physics. 

High school counselors are busy enough and have many interests to serve, so I didn't want to saddle them with the responsibility of communicating my belief that all college-bound students should be in physics. If you can get counselors on your side, all the better. But it never hurts to take the message directly to your market.

What About Colleagues Within the Science Department?

The greatest friction I encountered when gearing up was from teachers of chemistry and AP Biology. 

My campaign was multi-pronged, and a colleague in chemistry took exception to my changing the course description of physics to include the sentence, "Chemistry is not a prerequisite for physics." At the time, I was encountering difficulty from counselors who had a very traditional sense of the science sequence. I was looking to bypass their predilections. The chemistry colleague, I sense, was hoping to maintain market share despite the fact that honestly, chemistry is not a prerequisite for physics by any objective criterion.

Physics enrollment could reasonably be seen as a threat to AP Biology market share. In the '80s, a statement was issued from the California Community Colleges, California State University, and University of California academic senates. Its primary message for high school students was that they should take one year of biology, one year of chemistry, and one year of physics. 

An attempt was made to incorporate this dictum into our own policy for AP science enrollment, but the AP Biology teachers balked. They thought it would be perfectly reasonable for a student in a four-year high school to take biology, chemistry, and AP Biology—and be done with it as far as science was concerned.

So make no mistake: in posting the TAKE PHYSICS flyers around campus during course registration, you will be stepping on some toes. But are the objections of your colleagues reasonable? Or are they meritless attempts to protect turf? 

One early memory I have from a collegial scolding on the flyers was my suggestion that they advertise, too. They looked at me as if I had grown a second head. Mounting a campaign takes time and energy, and most of them had guaranteed enrollments. There was no way they were going to advertise. And since they weren't going to advertise, I shouldn't either. Status quo!

I chose to risk some bruised feelings and press ahead. Now my annual campaign is accepted as just another of my myriad quirks. When I initiated the campaign, my enrollment jumped from 4 to 6 sections.

Are There Any Pitfalls To Advertising?

Yes. 

Some are obvious. Keep all the slogans and pitches positive and pro-physics. Do not tinge any of them with negativity toward biology or chemistry. Don't turn them into campaigns promoting how cool you are: you're not running for office here. Students will find out how cool you are soon enough.

Some are less obvious. When my enrollment jumped from 4 to 6 sections, there was a problem. I can only teach 5 sections. The administration offered me a 6/5ths position. More students and no prep period. The fact that I'm still alive and teaching physics lets you know I turned that down. Then the counselors asked me to draw names from a hat to determine who'd be turned down. I refused to have any part of that. 

An administrator reminded me that I brought this trouble on by advertising. I reminded them that one of the reasons administrators get better chairs (and better compensation) was because they shouldered the burden of solving the problems I created. We hired an additional physics teacher the next year.

For more on this and related topics, see the posts on "recruitment."