Friday Four
Friday, February 20, 2015
1. This time last week, my daughter made
my Valentine's Day a day early. After leaving her in the family
room to perform a short chore, I heard her calling for
me.
"What is it, Pumpkin?", I said.
"I have a
secret!" she said, gliding by on her scooter in the next room and
wearing a big grin.
"What is it?"
"I love you!"
2. Another week, another myth bites the
dust. Remember that high-school chemistry lab demonstration of
sodium causing an explosion when dropped into a beaker of water? You
probably didn't get a complete explanation for why
that occurred:
High-speed cameras revealed a vital clue to what was fuelling the violent reaction in the early stages. The reaction starts less than a millisecond after the metal droplet, released from a syringe, enters the water. After just 0.4 ms, "spikes" of metal shoot out from the droplet, too fast to be expelled by heating. What's more, between 0.3 and 0.5 ms, this spiking droplet becomes surrounded by a dark blue/purple colour in the solution.There is a video at the link showing what the researchers found, and explaining the Coulombic explosion that results.
3. Apparently, phantom traffic jams were finally explained a few years back:
...Measurements on various motorways in Germany and Japan have shown that free-flowing traffic becomes congested when the density of cars reaches 40 vehicles per mile. Beyond that point, the flow becomes unstable and stop-and-go waves appear. Because it's founded in human reaction times, this happens regardless of the country or the speed limit. And as long as the total number of cars on the motorway doesn't change, the wave rolls backward at a predictable 12 mph.Experimental video appears at the above link.
Remember that the next time you reach the end of a long jam on the highway, only to find no apparent cause!
4. These geeky pick-up lines (courtesy of Snedcat) are all priceless. I especially like the seventh.
-- CAV
2 comments:
Regarding phantom traffic jams, Gus, can we safely guess that once automated (driverless) automobiles become commonplace after 2050, we may expect government interventions. Attendant accidents and lawsuits will require adaptive regulations resulting in new variables:
1) Phantom traffic jams will then vary not only by country, but;
2) Particularly by numbers of lawyers per capita in those countries.
The government interventions won't wait until then. In fact, we might be lucky to have driverless cars at all: Just consider the recently-proposed FAA regs on drones, which read in part:
"Visual line-of-sight (VLOS) only; the unmanned aircraft must remain within VLOS of the operator or visual observer."
Automatic cars? Nah: We'll end up with cars that basically have fancy cruise-control.
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