I wonder if law enforcement ever considered using these as sort of pre-emptive spike strips.
A steam jet doesn’t burn the broom; it cuts it.
For that, they usually just use human officers with knives.
This may make it clearer to some people.
\displaystyle \frac{2 lb}{1} * \frac{16 oz}{1 lb} = ?
The lb’s cancel out, leaving us with
\displaystyle \frac{2}{1} * \frac{16 oz}{1} = 32 oz
I wasn’t quite sure about this method when I learned it in high school until I realized lb and oz can be considered as variable names. Change “lb” to “y” and “oz” to “z”, and you have a basic algebra statement, so the y’s cancel out.
Absolutely correct, this is the standard way of teaching how to perform dimensional analysis, emphasizing the need to show all units and cancel as you go.
My point above was simply to show why this works: specifically that the conversion factor here (and all conversion factors, for that matter) are equal to a dimensionless “1”.
To see this, start with an equality:
\displaystyle 16 oz = 1 lb
Divide both sides of the equation by \displaystyle 1 lb:
\displaystyle \frac{16 oz}{1 lb} = \frac{1 lb}{1 lb}
End up with a conversion factor that is equal to 1:
\displaystyle \frac{16 oz}{1 lb} = 1
\displaystyle \frac{16 oz}{lb} = 1
\displaystyle {16 oz}/{lb} = 1
So the bottom line is that the reason that you can multiply things by conversion factors and not fundamentally change the result is because the conversion factors are numerically equal to a dimensionless “1”. And multiplying things by 1 does not change the result.
Anyway, in practice you do dimensional analysis exactly as you state, canceling units as you go.
TIL I learned about the Intermediate Film System,
… a television process in which motion picture film was processed almost immediately after it was exposed in a camera, then scanned by a television scanner, and transmitted over the air. This system was used principally in Britain and Germany where television cameras were not sensitive enough to use reflected light, but could transmit a suitable image when a bright light was shone through motion picture film directly into the camera lens.[1]
Intermediate film system for Remote Truck (1934), 1 - movie camera; 2 - film processor; 3 - washing bath; 4 - film drying compartment; 5 - telecine; 6 - monitor; 7 - video output; 8 - sewage; 9 - plumbing.
Frankly, I’m stunned that they were able to process, fix, and dry motion picture film in a continuous strip in as little as one or two minutes.
The video systems in question were the absurd mechanical rotating disk systems developed by Baird and his German counterparts, not the electronic scanning system invented by Philo Farnsworth and stolen by RCA that eventually became the basis for real television. Electronic systems made this weird, cumbersome kluge obsolete by 1937.
Someone doubts all those alleged right snobbish ways to pronounce places. Maybe he is onto something.
…(or early versions thereof) have been around for longer than you think.
A spike strip (spike belt, traffic spikes, tire shredders, stingers, stop sticks, Stinger or formally known as a tire deflation device) is a device or incident weapon used to impede or stop the movement of wheeled vehicles by puncturing their tires….
…They are historically a development of the caltrop, with anti-cavalry and anti-personnel versions being used as early as 331 BC by Darius III against Alexander the Great at the Battle of Gaugamela in Persia.
From: Spike strip - Wikipedia
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The Mont St. Michel sundial link dates from 2007. The setup may have been temporary, since there is no evidence of it on Google Streetview. Maybe it was/is visible only at low tide?
Admission to the New York World’s Fair of 1939-40 was 75 cents.
For comparison, minimum wage was 30 cents an hour.
Less an interesting fact than an interesting story. But the headline kind of tells it all. One in each uterus? It sounds like some kind of prophecy being fulfilled. I hope everyone is healthy and happy afterwards.
A typical airplane has its center of mass positioned forward of the wings’ center of lift, and uses the horizontal stabilizer (at the rear of the aircraft) to generate downforce so that the nose of the plane remains at the desired pitch. This is a fundamentally stable arrangement: if the aircraft’s speed drops, the h-stabilizer creates less downforce, the nose drops, and the aircraft picks up speed again. If the aircraft picks up too much speed, the h-stabilizer creates more downforce and picks up the nose, reducing speed.
For increased maneuverability and efficiency, you can design an aircraft with relaxed stability:
Many modern fighter aircraft position their center of mass to the rear of the wings’ center of lift for crazy maneuverability. Similarly a number of commercial airliners now position their center of mass close to the wings’ center of lift to achieve better fuel economy. These configurations are made possible by fly-by-wire systems, in which a computer makes constant adjustments to the flight controls to keep the aircraft from tumbling out of control.
All neat stuff to think about, but that’s not the random interesting fact I stumbled across. The random fact that I stumbled across is that birds have negative stability, as shown in this 2-minute video revealing the fluid mechanics behind what their wings and tailfeathers are doing during flight. They trained birds to fly through a cloud of particles, and illuminated those particles with a sheet of light to reveal air movements in the immediate aftermath of their passage. The footage reveals the usual wingtip vortices swirling downward, but it also showed a second set of downward-moving vortices, indicating that the tailfeathers are generating downforce during flight. Cool.
The doctor says she could potentially give birth to each baby at different times:
“Each uterus can contract on its own at different times,” Davis said. "It could be that one side contracts, and the other side is not doing anything.
That’s surprising to me. I thought uterine contractions were driven hormonally, so I wouldn’t think separate labors were possible.
It’s not like we have a large enough sample size to know much for sure. You don’t think it’s possible?
My limited understanding of how labor works would have led me to believe it was not possible. This OB says it is, so the most likely explanation is that my understanding of how labor works is flawed. That doesn’t make it less surprising to me.
I have heard that the baby determines when labor starts, rather than the mom*. It would be interesting to see how this plays out if the two babies decided to come out at separate times.
*nowadays, sometimes it’s the doctor that determines when labor starts
If “the baby determines when”, then it has to be hormonal, because there’s no neural connection between the baby and mother. But both uteri would be subject to the same hormones.
That said, my suspicion here is that the doctor was using a scientist’s maybe, not a layman’s: One might expect that both would contract together, it might be most likely that both would contract together, but “most likely” doesn’t mean “always”. As this situation itself illustrates. If the only thing that ever happens is the most likely, then you wouldn’t have a woman with two uteri to begin with.
My friend was talking about this some while back. Babies being born at whenever intervals became inconvenient for OBs, so they started doing more and more inducements, Nothing worse than being in the middle of the 14th and have to go rushing off to maternity because some random foetus decided it wanted out.
The issue involves, AIUI, a surfactant that coats the inside of the lungs to facilitate air breathing, as a natural prelude to birthing, which inducement apparently bypasses or abbreviates. Children who are induced may be more susceptible to breathing problems.
Ocean Spray cranberry cans are purposely labeled upside down.
“Ocean Spray, purveyor of canned cranberry sauce that comes out in the shape of a can and then jiggles its way onto our plates every Thanksgiving, has taken note of this common inquiry and, blessedly, has put our curiosity to rest. The company first posted this video to TikTok back in 2021 explaining the phenomenon, and has been diligently spreading the word again this year.”
Crazy youtube commercial.
"https://www.youtube.com/watch?v=MvyaFz39ilI&ab_channel=ReelChicagoReel360
Yep. That’s true.