Monthly Archives: June 2009

They Won't Wear a Leather Outfit, Either

Posted on by

Why a Greyhound or a Racehorse Doesn’t “Pop a Wheelie”

The ability to gain speed quickly is crucial for survival, but there’s a limit as to how rapidly an animal can accelerate. Researchers wondered whether the “wheelie” problem experienced by cars during a drag race could be a factor in four-legged animals’ ability to speed up. They came up with a simple mathematical model… to see how fast a quadruped could accelerate without tipping over backward. The model predicts that the longer the back is in relation to the legs, the less likely a dog is to flip over and the faster it can accelerate. Then the researchers tested the model by going down to the local track, London’s Walthamstow Stadium, and video-recording individual greyhounds as they burst out of the gate in time trials. The acceleration approached–but never exceeded–the limit predicted by the model

Hey You, Stop Being … so … Unsafe!

Posted on by

Over at incoherently scattered ponderings, there’s a post on safety at academic labs, which links to an article at Slate about an explosion at a lab which killed a worker, and discusses the difference in safety standards for students vs workers, and academia vs industry.

Why the difference between industry and academe? For one thing, the occupational safety and health laws that protect workers in hazardous jobs apply only to employees, not to undergraduates, graduate students, or research fellows who receive stipends from outside funders. (As a technician, Sheri Sangji was getting wages and a W-2. If she’d been paying tuition instead, Cal/OSHA could not even have investigated her death.)

I had not realized that students aren’t covered, but the disparity between the described situations is not surprising. I’ve spent time in academia (grad school) and worked in national labs (the NanoFabrication facility at Cornell, TRIUMF in Canada), and my current government job is a confluence of being industry/government and a quasi-national-lab (though not formally recognized as such). And I have to concur: lab safety in a university setting is not formally the priority is is in those other places. Academic safety leans far too much on the involvement of the PI, and leaves way too much to chance. A key difference of academia is that students are … students — they are still learning, and one cannot assume that they have the requisite experience to know much about the finer points of safety.

Continue reading →

Cause and Effect

Posted on by

Dean Dad asks

Why do so many states require only two years of math in high school?

[…]

We have anecdotal evidence that suggests that students who actually take math for all four years of high school do better in math here than those who don’t. We also have anecdotal evidence that bears crap in the woods. Why the hell do the high schools only require two years of math?

And there is followup at Uncertain Principles

There is a lot of discussion, so I may have missed someone raising the following point:

People who take four years of math and do well are probably good at math. Whatever distribution of students took the math for two years, I’d bet that it’s not the same as the distribution who took it for four. I’ll bet the players who go out for (pick your sport) do better at that sport in gym than the players that don’t, because you tend not to pursue and enjoy an activity if you suck at it.

The discussion seems to be dealing more with the other reasons why schools don’t require four years of math. I can ignore that for a moment and still assume an ideal case not limited by the availability of teachers or caused by bureaucracy. To me, the proposed solution embedded in the rhetorical question is not the head-slap obvious conclusion.

Blackbird Singing in the Dead of Night

Posted on by

The Ultimate Spy Plane

One nit:

Created as the ultimate spy plane, the SR-71, which first took to the air in December 1964, flew reconnaissance missions until 1990, capable of hurtling along at more than Mach 3, about 2,280 miles per hour—faster than a rifle bullet—at 85,000 feet, or 16 miles above the earth. It is the fastest jet-powered airplane ever built.

Mach 3 is about 2280 mph … at sea level. But it varies with density altitude, so at 85,000 feet, it’s about 2000 mph. The speed of sound, i.e. Mach 1, is not a constant of nature — it’s defined by the conditions (as opposed to the speed of light, which is c in a vacuum)