METRIC ^{4} US! |
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Why would we want the metric system? |
Let's face it: The metric system is the better system!
Why better? |
Because it's so much simpler and easier to use.
The metric system is an improvement over the English system in three major points:
- One unit of measurement for each physical quantity. No matter from which other quantities of the SI system derived, yields always the same unit.
- Scalability by prefixes - combinations of prefix and unit make for a plethora of convenient combined units.
- Decimal system - fractions are expressed in decimal notation. Not only makes this the notation unique, exhaustive and intuitively comparable, but also allows unit conversion without doing math - simply by shifts of the decimal point.
Why is this better? |
Let's compare the metric system with the English system in these three points to show why the metric system is better:
One unit of measurement for each physical quantity
To compare both systems here, we will list all English Imperial units in use, and all SI units describing the same range of the same physical quantities. These are: Length, area, volume, mass, force, pressure, energy, power and temperature. For a fair comparison, we omit those SI units which are commonly used in both systems, like second, ampere, volt, ohm etc.
To measure the above mentioned quantities in the English Imperial system, all the following units can occur:
- Length: inch, foot, yard, mile, fathom, rod, furlong, league, mil, pole, perch, hand, link, chain
- Area: square inch, square foot, square yard, acre, square mile, township, square fathom, square rod, square furlong, square league, square mil, square pole, square perch, square hand, square link, square chain
- Volume: gallon, liquid quart, dry quart, liquid pint, dry pint, fluid ounce, teaspoon, tablespoon, minim, fluid dram, gill, peck, bushel, cubic inch, cubic foot, cubic yard, cubic fathom, cubic rod, cubic furlong, cubic mile, cubic league, cubic mil, cubic pole, cubic perch, cubic hand, cubic link, cubic chain
- Mass: pound, apoth. pound, ounce, apoth. ounce, dram, apoth. dram, grain, spoth. scruple, pennyweight, short hundredweight, long hundredweight, short ton, long ton
- Force: pound, ton
- Pressure: pounds per square inch, pounds per square foot, pounds per square yard, pounds per acre, pounds per square mile, pounds per township, pounds per square fathom, pounds per square rod, pounds per square furlong, pounds per square league, pounds per square mil, pounds per square pole, pounds per square perch, pounds per square hand, pounds per square link, pounds per square chain, tons per square inch, tons per square foot, tons per square yard, tons per acre, tons per square mile, tons per township, tons per square fathom, tons per square rod, tons per square furlong, tons per square league, tons per square mil, tons per square pole, tons per square perch, tons per square hand, tons per square link, tons per square chain
- Energy: calorie, inch-pound, foot-pound, yard-pound, mile-pound, fathom-pound, rod-pound, furlong-pound, league-pound, mil-pound, pole-pound, perch-pound, hand-pound, link-pound, chain-pound, inch-ton, foot-ton, yard-ton, mile-ton, fathom-ton, rod-ton, furlong-ton, league-ton, mil-ton, pole-ton, perch-ton, hand-ton, link-ton, chain-ton
- Power: horsepower, inch-pound per second, foot-pound per second, yard-pound per second, mile-pound per second, fathom-pound per second, rod-pound per second, furlong-pound per second, league-pound per second, mil-pound per second, pole-pound per second, perch-pound per second, hand-pound per second, link-pound per second, chain-pound per second, inch-ton per second, foot-ton per second, yard-ton per second, mile-ton per second, fathom-ton per second, rod-ton per second, furlong-ton per second, league-ton per second, mil-ton per second, pole-ton per second, perch-ton per second, hand-ton per second, link-ton per second, chain-ton per second
- Temperature: degrees Fahrenheit
To measure the same range of the same quantities in the metric system, only the following units can occur:
- Length: meter
- Area: square meter (are)
- Volume: cubic meter (liter)
- Mass: gram (metric ton)
- Force: newton
- Pressure: pascal
- Energy: joule
- Power: watt
- Temperature: kelvin (degrees Celsius)
combined with none or one of the following prefixes:
micro, milli, centi, deci, deca, hecto, kilo, megaNow judge for yourself which units are easier to keep in your head — the mess of the English system, or the simple metric units!
Human beings can handle small whole numbers (0 to 999) better than huge numbers (e.g. 190080000), decimals (e.g. 0.672) or fractions (e.g. 77/256). That's why you want units that are close to the size of the thing you are measuring, so the resulting value is most likely to be a small whole number.
The English system addresses this problem by specifying all kinds of distinctly named, arbitrarily sized units. This causes two problems:
First, due to the unsystematic definition of the units, conversion between units is nearly impossible, as
- you have to remember all the unit names
- remember the chaotic plethora of conversion factors between them
- worst of all - multiply and divide by them!
And please don't say you don't have to convert between units because you do have to!
Have a look at the following three tables showing all the weird conversion factors you would need to know to convert between not even all, but only the most common English Imperial units of the most important three quantities — length, volume and mass. Bold face numbers are key factors. Here goes a glance of the insanity of the English Imperial system:
LENGTH mils inches links feet yards fathoms rods chains furlongs miles leagues mil 1 1/1000 1/7920 1/12000 1/36000 1/72000 1/198000 1/792000 1/7920000 1/63360000 1/190080000 inch 1000 1 25/198 1/12 1/36 1/72 1/198 1/792 1/7920 1/63360 1/190080 link 7920 7 23/25 1 33/50 11/50 11/100 1/25 1/100 1/1000 1/8000 1/24000 foot 12000 12 1 17/33 1 1/3 1/6 2/33 1/66 1/660 1/5280 1/15840 yard 36000 36 4 6/11 3 1 1/2 2/11 1/22 1/220 1/1760 1/5280 fathom 72000 72 9 1/11 6 2 1 4/11 1/11 1/110 1/880 1/2640 rod 198000 198 25 16 1/2 5 1/2 2 3/4 1 1/4 1/40 1/320 1/960 chain 792000 792 100 66 22 11 4 1 1/10 1/80 1/240 furlong 7920000 7920 1000 660 220 110 40 10 1 1/8 1/24 mile 63360000 63360 8000 5280 1760 880 320 80 8 1 1/3 league 190080000 190080 24000 15840 5280 2640 960 240 24 3 1
VOLUME minims fluid drams teaspoons tablespoons cubic inches fluid ounces gills cups liquid pints dry pints liquid quarts dry quart gallons pecks cubic feet bushels cubic yards minim 1 1/60 1/80 1/240 77/20480 1/480 1/1920 1/3840 1/7680 385/3440672 1/15360 385/6881344 1/61440 385/55050752 77/35389440 385/220203008 77/955514880 fluid dram 60 1 3/4 1/4 231/1024 1/8 1/32 1/64 1/128 5775/860168 1/256 5775/1720336 1/1024 5775/13762688 77/589824 5775/55050752 77/15925248 teaspoon 80 1 1/3 1 1/3 77/256 1/6 1/24 1/48 1/96 1925/215042 1/192 1925/430084 1/768 1925/3440672 77/442368 1925/13762688 77/11943936 tablespoon 240 4 3 1 231/256 1/2 1/8 1/16 1/32 5775/215042 1/64 5775/430084 1/256 5775/3440672 77/147456 5775/13762688 77/3981312 cubic inch 265 75/77 4 100/231 3 25/77 1 25/231 1 128/231 32/231 16/231 8/231 3200/107521 4/231 1600/107521 1/231 200/107521 1/1728 50/107521 1/46656 fluid ounce 480 8 6 2 1 103/128 1 1/4 1/8 1/16 5775/107521 1/32 5775/215042 1/128 5775/1720336 77/73728 5775/6881344 77/1990656 gill 1920 32 24 8 7 7/32 4 1 1/2 1/4 23100/107521 1/8 11550/107521 1/32 5775/430084 77/18432 5775/1720336 77/497664 cup 3840 64 48 16 14 7/16 8 2 1 1/2 46200/107521 1/4 23100/107521 1/16 5775/215042 77/9216 5775/860168 77/248832 liquid pint 7680 128 96 32 28 7/8 16 4 2 1 92400/107521 1/2 46200/107521 1/8 5775/107521 77/4608 5775/430084 77/124416 dry pint 8936 312/385 148 5468/5775 111 1367/1925 37 1367/5775 33 1921/3200 18 3571/5775 4 15121/23100 2 15121/46200 1 15121/92400 1 107521/184800 1/2 107521/739200 1/16 107521/5529600 1/64 107521/149299200 liquid quart 15360 256 192 64 57 3/4 32 8 4 2 1 77279/107521 1 92400/107521 1/4 11550/107521 77/2304 5775/215042 77/62208 dry quart 17873 239/385 297 5161/5775 223 809/1925 74 2734/5775 67 321/1600 37 1367/5775 9 3571/11550 4 15121/23100 2 15121/46200 2 1 15121/92400 1 107521/369600 1/8 107521/2764800 1/32 107521/74649600 gallon 61440 1024 768 256 231 128 32 16 8 6 94074/107521 4 3 47037/107521 1 46200/107521 77/576 11550/107521 77/15552 peck 142988 372/385 2383 863/5775 1787 697/1925 595 4547/5775 537 121/200 297 5161/5775 74 2734/5775 37 1367/5775 18 3571/5775 16 9 3571/11550 8 2 15121/46200 1 107521/345600 1/4 107521/9331200 cubic foot 459603 9/77 7660 4/77 5745 3/77 1915 1/77 1728 957 39/77 239 29/77 119 53/77 59 65/77 51 46029/107521 29 71/77 25 76775/107521 7 37/77 3 23037/107521 1 86400/107521 1/27 bushel 571955 333/385 9532 3452/5775 7149 863/1925 2383 863/5775 2150 21/50 1191 3319/5775 297 5161/5775 148 5468/5775 74 2734/5775 64 37 1367/5775 32 9 3571/11550 4 1 21121/86400 1 107521/2332800 cubic yard 12409284 12/77 206821 31/77 155116 4/77 51705 27/77 46656 25852 52/77 6463 13/77 3231 45/77 1615 61/77 1388 60052/107521 807 69/77 694 30026/107521 201 75/77 86 84394/107521 27 21 74859/107521 1
MASS grains apoth scruples pennyweights drams apoth drams ounces apoth ounces apoth pound pounds short hundredweights long hundredweights short tons long tons grain 1 1/20 1/24 32/875 1/60 2/875 1/480 1/5760 1/7000 1/700000 1/784000 1/14000000 1/15680000 apoth scruple 20 1 5/6 128/175 1/3 8/175 1/24 1/288 1/350 1/35000 1/39200 1/700000 1/784000 pennyweight 24 1 1/5 1 768/875 2/5 48/875 1/20 1/240 3/875 3/87500 3/98000 3/1750000 3/1960000 dram 27 11/32 1 47/128 1 107/768 1 175/384 1/16 175/3072 175/36864 1/256 1/25600 1/28672 1/512000 1/573440 apoth dram 60 3 2 1/2 2 34/175 1 24/175 1/8 1/96 3/350 3/35000 3/39200 3/700000 3/784000 ounce 437 1/2 21 7/8 18 11/48 16 7 7/24 1 175/192 175/2304 1/16 1/1600 1/1792 1/32000 1/35840 apoth ounce 480 24 20 17 97/175 8 1 17/175 1 1/12 12/175 3/4375 3/4900 3/87500 3/98000 apoth pound 5760 288 240 210 114/175 96 13 29/175 12 1 144/175 36/4375 9/1225 9/21875 9/24500 pound 7000 350 291 2/3 256 116 2/3 16 14 7/12 1 31/144 1 1/100 1/112 1/2000 1/2240 short hundredweight 700000 35000 29166 2/3 25600 11666 2/3 1600 1458 1/3 121 19/36 100 1 25/28 1/20 5/112 long hundredweight 784000 39200 32666 2/3 28672 13066 2/3 1792 1633 1/3 136 1/9 112 1 3/25 1 7/125 1/20 short ton 14000000 700000 583333 1/3 512000 233333 1/3 32000 29166 2/3 2430 5/9 2000 20 17 6/7 1 25/28 long ton 15680000 784000 653333 1/3 573440 261333 1/3 35840 32666 2/3 2722 2/9 2240 22 2/5 20 1 3/25 1 Now be amazed how few numbers you need to remember to measure the same range of the same quantities (length, volume, mass) in the metric system:
Prefix Symbol In Words Shift Point From To micro µ a millionth 6 <— —> milli m a thousandth 3 centi c a hundredth 2 deci d a tenth 1 deca da ten 1 —> <— hecto h a hundred 2 kilo k a thousand 3 mega M a million 6 As there is only one unit of measurement per quantity, conversions between units are merely conversions between prefixes. Once you can convert one prefix to another, you can practically convert all SI units among each other.
For volume and mass, there are two additional customary metric units except the standard units, but these are really only shortcuts for standard units: The liter is nothing else but a cubic decimeter, and the ton nothing else but a megagram.
So how to convert between these prefixes?
Just shift the decimal point - no math required!
To convert for example 1852 meters to kilometers, just shift the decimal point 3 places left = 1.852 kilometers! A snap! To convert back, just shift 3 places back right again. Even to convert across prefixes is no deal at all: Convert 160934.4 centimeters to kilometers by first shifting the point 2 places left from centi, then another 3 places left to kilo = 1.609344 kilometers, done! Just imagine in comparison to convert inches to miles - you'd have to divide by 63360!
So — which of the two sets of tables would you rather learn by heart and use? An insane chaos of arbitrary fractions which you have to multiply and divide by, or a systematic scheme needing only shifts of the decimal point!
And this is not all: The English units only cover a very limited range of measurement — for length the smallest unit you get is the mil, the largest the league.
The prefix system allows you to size up or down metric units to almost any size you possibly ever need — without having to know special unit names for each and every physical quantity. Learn the prefixes once, and they work for every possible unit. This is the complete table:
Prefix Symbol In Words Shift Point From To yocto y a septillionth 24 <— —> zepto z a sextillionth 21 atto a a quintillionth 18 femto f a quadrillionth 15 pico p a triillionth 12 nano n a billionth 9 micro µ a millionth 6 milli m a thousandth 3 centi c a hundredth 2 deci d a tenth 1 deca da ten 1 —> <— hecto h a hundred 2 kilo k a thousand 3 mega M a million 6 giga G a billion 9 tera T a triillion 12 peta P a quadrillion 15 exa E a quintillion 18 zetta Z a sextillion 21 yotta Y a septillion 24 As you can see, it doesn't really get more complicated - only you have more possibilities!
In fact, as the English system was designed to master nothing more than medieval measurement tasks, and also lacks the capability of systematic extension like the prefixes of the metric system, the English system fails to provide suitable units for numerous modern measurements. So wavelength of light, power of radiation, mass of blood cells and many more have to be measured in metric units, isn't that funny?
The decimal system is nothing new - you use it every day when you deal with money. Something might cost 4.98 Dollars or 0.45 Dollars.
The decimal system is superior to the fractional system, because
- You can immediately see which of two values is greater. While you can readily see that for example 0.33 Dollars is greater than 0.31 Dollars, you have to twist your brain to figure out that 1/3 (= 0.33) inch is greater than 5/16 (= 0.31) inches. Or, take three imperial drill bits: the 5/32, the 1/8 and the 9/64 - and take the equivalent metric drill bits: the 4.0, the 3.0 and the 3.5 - wouldn't you agree that the metric specification makes the drill sizes clear and evident, letting you readily see not only which one's the biggest or the smallest, but also by how much each drill is bigger than the other - while with the English specification you have to tie a knot into your brain to figure out not only which one's the biggest, but let alone imagining the sizes of the drills?
- You can easily add and subtract decimal numbers. It's a snap to add 0.33 Dollars plus 0.31 Dollars = 0.64 Dollars! But add 1/3 inch and 5/16 inches and find the result to be a confusing 31/48 inches! (and - would you know how to get to this result?) How about subtracting them: 0.33 Dollars minus 0.31 Dollars is simply 0.02 Dollars, while 1/3 inch minus 5/16 inches equals 1/48 inch! Imagine things in the supermarket were sold by fractions of a Dollar: You have one Dollar, and you want to buy a pound of bananas and one of apples. Bananas are 5/8 Dollars a pound while apples are 1/3 Dollar. Can you buy both? Now that you will agree that this would be a braindamaged system to measure prices in, yet you use it to measure length, volume, mass and many more things! Disregarding the fact that it's a pain in the neck to add or subtract fractions, most people wouldn't even know how to do it!
- Each number has exactly one decimal representation. While you write 0.4 in decimal, with fractions you can write 2/5, 4/10, 6/15 etc. etc. making it obscure to identify equal values. Sure, 9/64 plus 7/64 is 16/64, but don't forget that 16/64 is actually the same as 8/32, 4/16, 2/8 and, eventually 1/4!
- Decimal is native to measurement, as it makes the value's precision evident. Every measurement involves precision. Say the length of a fence is 45.413 meters, but not for every job you need to know the value so exactly - e.g. depending on if you actually want to replace the fence with the exact same size new one and have it cut in the shop, or you just want to have rough idea to estimate how much paint you need, you can say either 45.413 m, 45.41 m, 45.4 m or just 45 m, making it clear that the measurement is to a millimeter's, a centimeter's, a decimeter's or just a meter's precision.
You already use the decimal system for calculating with money - so you know it anyway! As it's the easier system, why not forget all the convoluted fractions and just use decimals!