Metric system primary units

The SI (metric) system of units is the primary one for the text. Because the Btu-ft-pound system is still in wide use, answers and intermediate steps to examples are occasionally stated in these units. A few examples and problems are completely in English units. Some figures have dual coordinates that show both systems of units. These displays will enable the student to develop a bilingual capability during the period before full metric conversion is achieved. 

In the metric system, the three primary or fundamental units are the meter for length, the liter for volume, and the gram for weight. In addition to these... 

The metric system and its more modem counterpart SI (for Systeme International d Unites) are systems of units designed to make calculations as easy as possible. It was designed to make every word mean one and only one thing. Its subdivisions and multiples of units are powers of 10 times a primary unit. Each of its prefixes means the same thing, no matter what unit it is attached to. The abbreviations for the quantities and prefixes are easy to remember. All these features have been built into the metric system to make it easy. Contrast this lack of ambiguity with the ambiguity in the English system, as illustrated in Example 2.4. 

The meter is the primary unit of length in the metric system. Its abbreviation is m. The meter is defined in such a way that it can be duplicated precisely in any well-equipped laboratory in the world. It had been defined as the distance between two marks on a metal bar kept at the Bureau of Weights and Measures in Paris. (It now has an even more precise definition.) A meter is 39.37 in. long—3.37 in. longer than a yard. 

The cubic meter (m ) is the primary unit of volume in SI. A smaller unit, the liter, is the primary unit of volume in the metric system. The abbreviation for hter is L. We need to know both the cubic meter and the liter. Table 2.3 summarizes the primary metric units of distance, mass, and volume. 

The primary unit of length in the metric system is the meter, which is 3.37 in. longer than a yard. The same prefixes are used with the meter as with all other metric units. 

As stated earlier, the primary unit of mass in the metric system is the gram. Because the gram is so small, however, the standard mass in SI and the legal standard in the United States is the kilogram. 

The metric system and its newer counterpart, SI, use subunits and multiples of units that are equal to powers of 10, and they also use the same prefixes to mean certain fractions or multiples, no matter what primary unit is being modified. The meter is the primary unit of length the gram is the primary unit of mass and the liter (the cubic meter in SI) is the primary unit of volume. The prefixes centi-(0.01), (0.001), and kilo (1000) are used with any of... 

ASTM Standard E380, Metric Practice Guide, provides a description of the International System of Units and deals with the conversion of quantities expressed in various systems of measurement to SI units. It includes a list of references to many primary sources of information on the International System of Units. 

---