Metric system equivalents

Micron— A unit of length in the metric system equivalent to one-millionth of a meter. 

Equivalents of commonly used units for the U.S. Customary System and the metric system ... 

One major advantage of the metric system is that it uses a decimal system, which means all units are related to smaller or larger units by a factor of 10. Some of the more commonly used prefixes along with their decimal equivalents are shown in Table 1.2. From this table, you can see that 1 kilometer is equal to 1000 meters, where the prefix kilo- indicates 1000. Likewise, 1 millimeter is equal to 0.001 meter, where the prefix milli- indicates Xooo- You need not memorize this table, but you will find it a useful reference when you come across these prefixes in your course of study. 

At the time of writing, conversion from the Imperial (F.P.S) to metric system of units, especially in North America, is far from complete. Thus Imperial units have generally been used in the text with metric equivalents provided in brackets. In tables and figures, the system of units given in the original source (usually Imperial) has been retained. 

Medium and Heavy Wall Tbbing (Table 3.9 and Table 3.10). This tubing is made in English sizes, but with the push toward the metric system such tubing is now listed in catalogs in its metric equivalent (therefore, 1" tubing is listed as 25.4 mm). Both English and metric measurements are listed in both tables. 

Another common unit of measurement for natural gas is by use of its heating value, expressed in British thermal units (BTU) per standard cubic foot in the English system, and in Joules (or calories) per unit volume in the metric system. Commercially used natural gas, after processing, yields the equivalent of about 950-1050 BTU/ft3. Also used as a unit of measurement is the therm, equivalent to 100,000 BTU, or the nominal heat content of 100 standard cubic feet of lean, processed natural gas. 

The Metric System originated in France during the French Revolution, and its use has since been required or legalized in most civilized countries. The fundamental unit cf the system is the meter, which is approximately equal to the ten-millionth part of the distance from the equator to the north pole. This distance was ascertained by actual measurement of an arc of a meridian passing through Barcelona in Spain and Dunkirk in France. The legal equivalent of the meter in the United States is 39.37 inches. 

Liter, n. Unit of volume in the Metric System. A cubic decimeter, equivalent to looo cc., a kilogram, 2,2 lb., or 1.06 quarts of water. 

Eventually, ancient rules of thumb gave way to more carefully defined units. The metric system was adopted in France in 1799 and the British Imperial System of units was established in 1824. In 1893, the English units used in the United States were redefined in terms of their metric equivalents the yard was defined as 0.9144 meter, and so on. But English units continue to be used in the United States to this day, even though the Omnibus Trade and Competitiveness Act of 1988 stated that it is the declared policy of the United States...to designate the metric system of measurement as the preferred system of weights and measures for United States trade and commerce. ... 

Minutes are permitted to remain in the metric system for convenience or for historical reasons, even though they don t conform strictly to the rules. The minute, hour, and day, for example, are so customary that they re still defined in the metric system as 60 seconds, 60 minutes, and 24 hours— not as multiples of ten. For volume, the most common metric unit is not the cubic meter, which is generally too big to be useful in commerce, but the liter, which is one thousandth of a cubic meter. For even smaller volumes, the milliliter, one thousandth of a liter, is commonly used. And for large masses, the metric ton is often used instead of the kilogram. A metric ton (often spelled tonne in other countries) is 1,000 kilograms. Because a kilogram is about 2.2 pounds, a metric ton is about 2,200 pounds 10% heavier than an American ton of 2,000 pounds. Another often-used, non-standard metric unit is the hectare for land area. A hectare is 10,000 square meters and is equivalent to 0.4047 acre. 

Volumes are often measured in liters or milliliters in the metric system. One liter (1 L) is one cubic decimeter (1 dm ), or 1000 cubic centimeters (1000 cm ). One milliliter (1 mL) is 1 cm In medical laboratories, the cubic centimeter (cm ) is often abbreviated cc. In the SI, the cubic meter is the basic volume unit and the cubic decimeter replaces the metric unit, liter. Different kinds of glassware are used to measure the volume of liquids. The one we choose depends on the accuracy we desire. For example, the volume of a liquid dispensed can be measured more accurately with a buret than with a small graduated cylinder (Figure 1-13). Equivalences between common English units and metric units are summarized in Table 1-7. 

Mass describes the quantity of matter in an object. The terms weight and mass are often used interchangeably, but they are not equivalent. Weight is the force of gravity on an object. The fimdamental unit of mass in the metric system is the gram. One atomic mass unit (amu) is equal to 1.661 X... 

The metric system was modified as Systeme International (SI) units (Table 1.6) to prevent some confusion. The SI is based on seven fundamental units—including the mole, meter, kilogram, and second—from which the others are derived. The significant changes for soil chemistry are mole of ion charge for equivalent, siemens for mho, joule for calorie, and pascal for pressure. Table 1.4 summarizes the SI units most frequently encountered in sod chemistry. SI allows easier conversion and communication between disciplines, but unfortunately discards some useful and familiar units, such as angstrom and equivalent,... 

The SI base units are summarized in Table 1.12. The SI units comprise a rigorously coherent form of the metric system, i.e., all remaining units may be derived from the base units using formulas that do not involve any numerical factors. For example, the unit of force is the newton (N) a 1-N force will accelerate a 1-kg mass at 1 m/s2. Hence 1 N = 1 kgm/s2. The unit of pressure is the N/m2, often referred to as the pascal. In the SI system there is one unit of energy (thermal, mechanical, or electrical), the joule (J) 1 J = 1 N-m. The unit for energy rate, or power, is joules per second (J/s), where one J/s is equivalent to one watt (1 J/s = 1 W). 

It is often necessary to convert a given result from one system of units to another. The best way to do this is by a method called the unit factor method or, more commonly, dimensional analysis. To illustrate the use of this method, we will consider several unit conversions. Some equivalents in the English and metric systems are listed in Table 1.4. A more complete list of conversion factors given to more significant figures appears in Appendix 6. 

Units of weight, volume, and length are rendered with conventional English terms as shown in the table below. The table also shows the average and rounded-off equivalences in the Western metric system that apply between the Elan and the early Tang, the period covered by this book. 

The question mark stands for the number we want to find. To solve this problem, we must know the relationship between inches and centimeters. In Table 2.7, which gives several equivalents between the English and metric systems, we find the relationship... 

Students often have trouble relating measurements in the metric system to the English system they have grown up with. Give the approximate English system equivalents for each of the following metric system descriptions in Exercises 17-20. 

The unit of volume in the metric system is the liter, which consists of 1000 milliliters. How many liters or milliliters is each of the following common English system measurements approximately equivalent to ... 

Abbreviations Common units of measurement and other commonly abbreviated terms and designations should be abbreviated as listed below if any others are used often in a manuscript, they should be written out the first time used, followed by the normal and acceptable abbreviation in parentheses [e.g., Acceptable Daily Intake (ADI), Angstrom (A), picogram (pg)]. Except for inch (in.) and number (no., when followed by a numeral), abbreviations are used without periods. Temperatures should be reported as °C or °F (e.g., mp 41° to 43 °C). Because the metric system is the international standard, when pounds (lb) and gallons (gal) are used the metric equivalent should follow in parentheses. 

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