American Customary Measurements: Difference between revisions
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{{quote|''"The metric system is the tool of the devil! My car gets forty rods to the hogshead, and that's the way I likes it!"''|Grandpa, ''[[The Simpsons]]''<ref name="rods-to-hogshead">About 0.002 MPG.That's very, very, shitty.</ref>}}
36-24-36. (Maybe, if she's 5'3".)
Whereas in most of the world [[The Metric System Is Here to Stay|the metric system has come into near-universal use]] by ordinary citizens, the US retains a non-decimal system of measurement largely derived from traditional English units. Technically speaking, the US government has observed the metric system since it ratified the Convention on the Meter in the late 19th century, and indeed, the customary units described below are now legally defined in terms of their metric equivalents rather than their historical origins. The metric system is also almost universally used by the scientific community, though [[Unit Confusion]] has sometimes arisen when American and international teams each assumed one was using the other's units. To further complicate matters, the American engineering community has held on to customary units resulting in occasional disconnects between the builders and users of scientific equipment (for example, loss of the Mars Climate Orbiter, popularly attributed to unit confusion between American and European space agencies, was actually due in large part to this sort of thing <ref>Specifically, a software error - the thruster-control algorithms used force pounds, while the high-level software worked in Newtons, a problem caused by lack of communication between NASA and its contractors and exacerbated by lack of proper testing.</ref> ). What has come to be known as the "customary system", for lack of a better term, has continued in usage in the US for a number of factors, including tradition, national pride, and the expense of conversion. An attempt by Congress to mandate metric conversion in the 1970s failed primarily because of the last reason (and the lack of political will to ''insist''). Only the bottling industry switched, but not for that reason. One company (Dr Pepper) advertised the small size gain from 2 quarts to 2 liters, and all other companies followed, which is why 2 liter bottles (and more recently, 1 liter bottles) are in metric but smaller units are in Fluid Oz.
In Canada, Britain and other English-speaking countries, these units also enjoy non-official use (known as Imperial measurements, after the British Empire), though their defining values may be slightly different; an Imperial gallon, for example, is about 1.2 American gallons. This is, combined with mixing randomly with metric units, of course part of the secret British plan to confuse ''all'' foreign visitors. There's also some unofficial use in other countries, particularly in Latin America, where the close proximity to the USA means Imperial units are sometimes used instead of Metric units; engine power and torque, for example, is often measured in Europe in kilowatts and newtons-meter (kW and Nm), while in Latin America the former is sometimes measured in horsepower and the latter in pounds-foot. Car wheels (and tire inner dimensions) are almost universally measured in inches, worldwide. An abortive attempt was made to switch to metric in the early [[The Eighties|80s]]; at this writing (2008) only Michelin supplies tires to fit these sizes, in low volume at prices just short of exorbitant.
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The following is intended as a primer for non-Americans to whom the customary units of measurement may seem foreign, cryptic or simply hard to visualize. In modern times, most of these units are defined by their metric equivalents.
==Distance==
Since 1959, the foot has been internationally defined as exactly 30.48
Two smaller units, "points" and "picas", are used in graphic design and typesetting, and refer to one twelfth and one seventy-second of an inch. Outside those fields, one is liable to run into "points" in the context of [[Useful Notes/Fonts|font]] sizes (though the usage of point measurements for font sizes on a computer screen is mostly traditional and will not usually reflect the actual physical size of a
One notable exception to all of this is the US automotive industry. They standardized on metric fasteners in [[The Eighties]], and because of this, it's common to see both fractional-inch and metric sized sockets and wrenches in toolkits. Also, in some circles, lengths of less than a half-inch or so are given in millimeters because they're easier to work with; things like the tips on writing instruments and the width of photo film have been measured in mm for decades.
==Mass==
==Volume==
Spaces you don't expect to fill with liquid (car trunks, apartments, warehouses, etc.) are expressed in cubic
Cooks use three additional units: the teaspoon (5 mL), the tablespoon (15 mL), and the kitchen cup (240 mL), slightly more (or less in the Commonwealth) than the fluid cup above. Three teaspoons make a tablespoon, two tablespoons make about a fluid ounce, sixteen tablespoons make a cup, and two cups make a pint.
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Prior to the early 1970s, American automobile engines listed their displacement in cubic inches. (The "409" that the [[Beach Boys]] sung about was a car with a 409 cubic inch engine.) American cars have been built using metric measurements since the early 1970s, when the energy crisis lead to the downsizing of engines and it became preferable to advertisers to describe the size in liters rather than in cubic inches. but since some cubic inch-based engine sizes are closely related to former performance they still pop up now and then. When [[Vanilla Ice]] rapped about his "five oh," he was referring to the 5.0l Mustang, which was a heavily redesigned "302" that is really closer to 4.9l. Small block Chevy V8s are still closely associated with 350 c.i, although the company hasn't made one (or at least a 5.7l) in years.
==Temperature==
'''Temperature'''. The standard unit of temperature in the United States is the degree Fahrenheit (See below for Celsius equivalent). The boiling point of water at sea level is 212° and its freezing point is 32°. Fun fact: the distance between freezing and boiling is 180°; this was intended by Daniel Fahrenheit as it would make it easier to mark a rotary-gauge thermometer: 180 angular degrees could equal 180 temperature degrees.▼
[[File:Raumthermometer Fahrenheit+Celsius.jpg|thumb|A dual unit thermometer, Fahrenheit on the outside, Celsius on the inside.]]
▲
The mean body temperature of a healthy adult is approximately 98°-100° (an oft-quoted figure of 98.6° is really just an overprecise conversion from 37° Celsius.) Zero degrees is an arbitrary point, based on the lowest temperature that could be measured at the time the scale was developed, the approximate freezing point of seawater. Temperatures less than 0° are colloquially spoken as "X below"; thus, -10° would be "ten below". The Fahrenheit and Celsius scales coincide at -40°, and absolute zero is exactly -459.67°. To derive a Celsius temperature from a Fahrenheit reading, subtract 32 and divide by 1.8. An advantage to the Fahrenheit scale is the simplicity to the average person: 0° is really cold for a person and 100° is really hot, but both are within a range of temperatures you may experience over the year (in Europe and North America at least). There also exists the Rankine scale, which is largely a historical curiosity at this point. Like the Kelvin scale, it starts at absolute zero and uses the same size degree as the Fahrenheit scale, so water freezes around 491.67° and boils around 671.64°.
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American cookbooks specify temperatures exclusively in degrees Fahrenheit. Oven temperatures are always given in increments of 25 degrees, e.g. "Preheat oven to 425". The "gas mark" notation seen in British cookbooks is not used.
==Dates and Time==
As to dates, they are written in the month/day/year format instead of the European day/month/year. December
==Money==
[[File:2021-P US Quarter Obverse.jpg|thumb|A quarter. If a machine takes coins, it’s almost guaranteed to take quarters.]]
Other coins are the nickel, five cents; the dime, ten cents; the quarter, 25 cents; the half-dollar (guess); and various editions of a one-dollar coin. The half-dollar lost favor after 1965, and the dollar coin never really caught on. 50-cent pieces don't even fit in most vending machines, though dollar coins are sometimes given as change in the newer ones. Those not accustomed to US currency sometimes find it counterintuitive that the dime is physically smaller than the penny, and all the common dollar coins are similar in size to the quarter. (Dollar coins were larger than the half-dollar prior to 1979, but the half-dollar coin is already at or near the upper limit of how large a coin a person wants to carry around.) The size disparities are the legacy of pre-1965 silver coinage - the dime, quarter, half-dollar, and dollar were made from a silver alloy, and the dime weighed (and still does) 1/10 that of the "silver dollar". The nickel was and is still made of a copper-nickel alloy, hence the name; most dollar coins minted these days are at least intended to look golden. On top of that, the dime does not say "10 cents" on it; it says "one dime", and you're expected to figure out that that comes from the French for "one tenth" - di(s)me.
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Through most of U.S. history, there were four types of bills issued by the US government - ''silver'' and '' gold certificates'', ''United States Notes'', and ''Federal Reserve Notes''. The first two were specie-backed currency, meaning that their value was backed by an equivalent amount of the specific precious metal in their name. United States Notes, and Federal Reserve Notes before 1963, were redeemable in “lawful money,” which was never defined by Congress; the only difference between these two types of paper money was that one was issued by the U.S. Treasury and the other was issued by the Federal Reserve. Modern Federal Reserve Notes, which have been the only sort of paper money issued by the US Government since 1963, are ''fiat'' currency - their value is not backed by any hard resource, but by the "full faith and credit" of the U.S. Government.
==Energy==
The second is the kilowatt-hour (3.6 MJ), mostly used by electric companies. Most Americans know what a watt is through electrical device ratings, so to make things more intuitive, power meters in the US use this composite unit (the amount of energy used by a 1000-watt appliance in 1 hour) instead of measuring things directly in joules.
The third customary unit of energy in the United States is the calorie (~4.184 J), used in heating, nutrition, and kinesiology. An odd duck of sorts, the calorie, based on the specific heat of water, was introduced as a metric unit in 1824, but was displaced within the System Internationale by the joule - but not before it found usage within the United States. The unit most Americans refer to when they say "calorie"
There is also the "British Thermal Unit", normally abbreviated BTU, which is mainly used for things like specifying the amount of heat put out by furnaces. There are various definitions of the BTU, which range from about 1,054 to 1,060 J according to the other wiki. To make things even more confusing to outsiders, American Engineers measure cooling in tons (12,000 BTU/hr, equivalent to 1 ton of ice per day or ~3516.85 W) and heating in MBH (one thousand BTU/hr or ~293.07 W; the M is the Roman numeral for 1000, not the expected one million); both of those units are also technically measures of ''power'', not energy, but the BTU is an odd enough bird that it's better to keep everything together.
==Power==
All that said, you're unlikely to see horsepower used outside of the automotive (and the propeller aviation and helicopter aviation) realm or certain kinds of electrical motors. As noted above, all electrical appliances in the US specify their rated consumption in watts (or the equivalent in volts and amperes), especially light bulbs and pretty much anything with a heating element in it. Ads for things electronic also tend to boast about how many watts they can output, especially high-power audio amplifiers and, sometimes, even the radio stations themselves.
==Force==
==Torque==
==Pressure==
==Food labeling in the US==
'''Food labeling in the US:''' As mentioned above, the food industry was one of the few to <s>embrace</s> be legally required to use the metric system during the failed attempt at forced conversion in the US, so food packaging is, outside of school, the place where most Americans encounter the metric system. Since there are few laws regarding the use of metric units, different foods tend to use metric and American units in different ways on packaging. Most of the time, either the American or the metric unit will be indicated first, with its equivalent indicated thereafter in parentheses. Some examples are as follows:▼
[[File:US Nutritional Fact Label 2.svg|thumb|An annotated nutrition facts label. Note the metric units. The real deal is in black and white.]]
▲
Nutritional labels indicate energy content in kilocalories (confusingly, always labeled as "Calories". Note the capitalization; that's important.) and the amounts of other nutrients and additives in grams or milligrams. Vitamin content is typically indicated only as a percentage of the federally-recommended daily allotment. Since the format of nutritional labeling is set by the FDA, this is harmonious across all food products.
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Beverages sold in cartons or polyurethane jugs (dairy products and some fruit juices) are sold by the gallon, half-gallon, or quart. Milk often comes in Quarts, Half Gallons and Gallons,
Prescription drugs, on the other hand, are labeled in metric units, because the amounts in question are usually so tiny as to render the conventional units meaningless, plus the fact that we're deep into scientist territory here. One may occasionally find a medicine bottle with weight indicated in grains, though they're today extremely rare.
==Alcohol==
The alcoholic strength of spirits is described as a percentage of alcohol by volume, and, in the case of spirits, by "degrees proof", where 1 proof = 0.5% ABV. (Contrast British degrees proof, wherein 100 proof equals the point at which gunpowder moistened by the spirit is still capable of ignition, i.e. 57.15% a.b.v, or 114.3 American proof).
==Drugs==
Marijuana is usually purchased in weights measuring 1/8th of an ounce, or it is measured in grams for smaller quantities. The same goes for "magic" psilocybin mushrooms. Cocaine is sold by the gram or 8-ball, which is 3.5 grams (just under 1/8 of an ounce hence the name). LSD can come in liquid form, measured in micrograms, or is sold on cardboard strips known as "blotters." Drugs like Ecstasy typically come in quarter-gram pills, which are sold individually (though the weight of active MDMA in the pill will be substantially lower than that). There's an old joke that "drugs are God's way of teaching Americans the metric system."
Note that since drugs like Marijuana,<ref>medical marijuana is legal at the State level in California, but is still illegal at the Federal level</ref>
==Abbreviations==
* $: Dollars (confusingly, $ is also the abbreviation for Pesos in Mexico, which borders the U.S.). Appears ''before'' the number (except in Quebec).
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* mi: Miles
** Except for mph (miles per hour)
*** Not to be confused with the metric "m" for "meter".
* oz: Ounces
* yd: Yards
For those wondering, a hogshead is 63 U.S. liquid gallons, and a rod is 16.5 feet. 40 rods to a hogshead, as mentioned in the quote above, works out to approximately 120,000 liters per 100
In miles per gallon that's statistical zero.<ref
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[[Category:Useful Notes/The United States]]
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