It’s actually spelled a’a, pronounced “ah ah”
I’ve often – usually – seen it written without the apostrophe
Not sure if this was posted already, but:
Barcode scanners actually read in between the black lines, and not the black lines themselves.
Long ago I wrote software that read barcodes, and that’s not really the case though it depends on the barcode type. Both the thickness of the black lines and the white lines are used in most systems. For example, in UPC coding you can see that the combination of dark white areas are added together to make a numeric coding set, with a start/end/middle bar set bounding the numeric areas.
Yes, Hawaiian words are commonly written in English sans 'okina, but that doesn’t make it correct. If in doubt, ask someone from O’ahu that isn’t a haole.
In the Wikipedia sense of ‘correct’.
In the correct sense of correct. You can quibble about modern coinages in Hawaiian e.g. “Puʻu ʻŌʻō”, the volcanic vent on Kīlauea that opened just a few years ago, but a’a is a legit Hawaiian term that dates back so spelling it a’a is just plain correct. I’m not native Hawaiian so ask them but that’s my understanding.
In the worlds of crossword puzzles and scrabble the apostrophe is virtual.
In txtng lvng ot ltrs is vitl so is jst a.
That Al Gore and Tommy Lee Jones were roommates is an interesting fact in itself.
Hummingbirds, whatever the species, always lay two eggs at a time.
Nine-banded armadillos always give birth to identical quadruplets.
And, as such, given the fact that armadillos are one of the very few species who can contract Hansen’s Disease (aka leprosy), armadillos are indispensable in medical research on that condition.
Dick Cheney had no pulse for 15 months.
In early-July 2010, Cheney was outfitted with a left-ventricular assist device (LVAD) at Inova Fairfax Heart and Vascular Institute to compensate for worsening congestive heart failure.[214] The device pumped blood continuously through his body.[215][216] He was released from Inova on August 9, 2010,[217] and had to decide whether to seek a full heart transplant.[218][219] This pump was centrifugal and as a result he remained alive without a pulse for nearly fifteen months.[220]
If we are going to be strict about physics here, no usual lab instrument is actually measuring mass per se.
They all measure WEIGHT, ie the force exerted on the mass by gravity. Which of course can vary from place to place. Presumably precision weighing instruments need to be calibrated for local gravity?
Of course this is less of an issue for a lever-arm balance since gravity acts equivalently on the reference weights in the other pan.
And there are inertial mass balances which really do measure inertial mass by vibrating the test object, though you wouldn’t use one for general purposes.
You raise an interesting point - I have no idea if that is done, either explicitly or implicitly.
A quick google suggests that local gravity could vary from place to place by a fraction of a percent (0.7% and the max variation between extremes) - so one part in a thousand would certainly be credible. In the example I’m describing, that’s a specialised analytical balance, so any other weighings germane to the analytical procedure would be performed on the same balance or a nearby one. Even if it were not a nearby balance (and I suppose that’s possible) a difference of one or two parts in a thousand shouldn’t be a practical problem in the vast majority of cases.
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Hadn’t thought about it myself until I stumbled across the thread. Of course if one is mostly concerned about relative measurements (percentage analysis by weight) it’s not an issue as long as the same scale is used each time. But if one wants an “absolute” measurement, adjusting for local gravity matters.
I’m guessing that modern lab scales use some sort of electromagnetic solenoid to measure the force?
Lever-balances seem rather 19th century?
No doubt lab equipment manufactures are quite aware of the issue… anyone with any first-hand knowledge out there?
I know some digital scales can be calibrated with precise weights:https://www.amazon.com/American-Weigh-Scales-500WGT-Calibration/dp/B00SSK3YNO/
One of my math-y friends tells me that “Algorithm” is almost always a mathematical term, not the act of dancing like the former US vice-president.
Your fingers wrinkle from being in water, not from water being absorbed, but from blood being *squeezed out from vasoconstriction.
*Not squeezed out into the water, but from the finger/toe tips back into the blood vessels.
I’ve got some experience with scales and balances. Most scales use a strain gauge-based transducer called a load cell. They’re basically a chunk of metal with some electrically resistive foil glued on the surface in certain spots. This resistance changes when the chunk of metal is loaded and bends since the foil bends with it. The resistors are arranged in a wheatstone bridge configuration which results in a variable voltage output in relation to the load. In this regard, a normal scale can be boiled down to a power supply to the bridge (usually between 5 & 15 VDC) and a voltmeter to measure the output (usually from 0 to 40 millivolts). There is much R&D put into how the metal chunk is machined or otherwise shaped so as to make the change in voltage linear (or proportional to the load), repeatable, with minimal hysteresis (it returns to zero when unloaded), and relatively immune to reasonable off center loading which may twist the load cell instead of bending it. Load cell scales are by far the most common and most people outside of laboratory or some industrial environments have never interacted with any other type. Scales on deli counters and grocery checkouts, digital kitchen or bathroom scales, scales to weigh trucks, baggage at the airport, overhead lifting like on cranes or even digital fishing scales all use load cells.
However, things don’t bend in straight lines, they bend in curves. Technology is always improving but beyond a figure that is constantly getting better, the change in voltage in response to changes in loads simply isn’t linear if you measure it at higher and higher resolutions. Right now, this is about 100,000 divisions, though some load cell scales can exceed this by a bit. After that, you need to use different technology and the most common is magnetic force restoration. In short, an electromagnet lifts the applied load through a series of levers & milled flexure surfaces and a control system measures the current to the magnet which is correlated with force of which weight is a particular type. A basic, nothing special commodity balance may be 220 gram capacity by 0.0001 grams resolution. This is 2.2 million individual divisions and probably gettable for under $1500. A really sensitive balance (link to 2.1 x 0.0000001 gram balance) might have nearly 10x more graduations. That one will set you back about $35k so try not to drop it. It can also measure a change of weight by simply taking it up or down a few flights of stairs or driving it a few miles away due to distance from the center of earth or changes in local gravity.
Calibrating against a known load is critical in some applications. It probably doesn’t matter for some freight or a 3lb bag of potatoes but might at the compounding pharmacy or aerospace development or materials development lab. Very good instruments will have internal calibration: there’s a mechanism inside the instrument that can lower a known-value weight onto a holder and it self-adjusts. This can help knock out those day-to-day errors that occur due to changes in temperature, humidity, and tiny changes in the level of the surface the balance is sitting on.
Heh, that weight is, please forgive me, a piece of crap. There are different classes of weights which are held to higher standards as needed. Here’s one that weighs 1 milligram and costs almost $600. Granted, it’s made of platinum but its aluminum equivalent is over $300. What other product can you put a half billion dollars worth of into a coffee mug and isn’t by virtue of it’s material value (like a super rare isotope or ultrahighend compound).