Metric system mass/weight

The English system of units is complicated compared to the metric system. In the English system, the units of mass are pounds-mass (Ibm) and the units of weight are pounds-force (Ibf). By definition, a weight (i.e., force) of one Ibf equals the force produced by one Ibm under the acceleration of gravity. Therefore, the constant, g, which has the same numerical value as g (32.17) and units of Ibm-ft/lbf-sec, is used in the definition of weight ... 

Scientists measure many different quantities—length, volume, mass (weight), electric current, temperature, pressure, force, magnetic field intensity, radioactivity, and many others. The metric system and its recent extension, Systeme International d Unites (SI), were devised to make measurements and calculations as simple as possible. In this chapter, length, area, volume, and mass will be introduced. Temperature will be introduced in Sec. 2.7 and used extensively in Chap. 11. The quantities to be discussed here are presented in Table 2-1. Their units, abbreviations of the quantities and units, and the legal standards for the quantities are also included. 

The metric system, or Systeme International d Unites (SI system as it is commonly known), is the predominant system of measurement in the world. In fact, the United States is one of only about three countries that do not commonly use the metric system. The metric system attempts to eliminate odd and often difircult-to-remember conversions for measurements (5,280 feet in a mile, for example). It is a decimal-based system with standard terminology for measurements of length, volume, and mass (weight). It also uses standard prefixes to measure multiples of the standard units. 

In 1960 the International General Conference on Weights and Measures adopted an improved form of the metric system, The International System of Units (SI). The units of mass, length, and time are the kilogram (kg), meter (m), and second (s). The following prefixes are used for fractions and multiples ... 

Temperature. Temperature was not one of the original properties that the French academy deemed necessary to include in the metric system. In fact, as late as 1921, members of the 6th General Conference of the International System of Weights and Measures were still objecting to the inclusion of measurements (other than length and mass) seemingly for no other reason other than to keep the base units pure. ... 

Biochemistry employs a decade system of units based on the metric system. Thus, biochemists use units such as the mole or the liter and various subdivisions that differ by three orders of magnitude (Table 1-1). With knowledge of the molecular weight of a particular molecule and equation 1-1, a given mass of a molecule can be converted to units of moles ... 

The net quantity of contents (in terms of weight or mass, measure, or numerical count) shall be separately and accurately stated in a uniform location upon the principal display panel of that label, using the most appropriate units of both the customary inch/pound system of measure, as provided in paragraph (3) of this subsection, and, except as provided in paragraph (3)(A)(ii) or paragraph (6) of this subsection, the SI metric system ... 

SI is somewhat different than the CGS system, in use for many years, which has often been called the Metric System. SI is a system adopted internationally by the General Conference of Weights and Measures. Among some of the principles are the use of the kilogram for mass only, and the use of newton for force or weight. 

Gram A unit of mass and weight in the metric system, defined as one thousandth of a kilogram. (A kilogram is about 2.2 pounds.)... 

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... 

We shall first review the common units of weight and volume in the metric system and then describe methods of expressing results. The gram (g) is the basic unit of mass and is the unit employed most often in macro analyses. For small samples or trace constituents, chemists use smaller units. The milligram (mg) is 10 g, the microgram (/xg) is 10 g, and the nanogram (ng) is 10 g. The basic unit of volume is the liter (L). The milliliter (mL) is 10" L and is used conunonly in volumetric analysis. The microliter (/xL) is 10 L (10 mL), and the nanoliter (nL) is 10 L (1Q- mL). (Prefixes for even smaller quantities include pico for 10 and femto for 10" .)... 

The International System of Units, abbreviated as SI (from the French name Le Systeme International d Unites), was established in 1960 by the 11th General Conference on Weights and Measures (CGPM) as the modern metric system of measurement. The core of the Si is the seven base units for the physical quantities length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity. These base units are ... 

Science progressed more rapidly in the last 200 years than it had in the few thousand years previous. A great deal of this success came from the agreement among scientist to create and use a set of standard conventions. The two most important conventions are the periodic table and the international system of units, called SI units. SI units are based on the metric system, and it s more common to see temperature expressed as Celsius than Fahrenheit. And you see lengths expressed in meters instead of inches and feet. Weights and mass are expressed in terms of grams instead of pounds or stone. 

The standard masses (standard weights) in the metric system are calibrated (checked) by comparison with the standard kilogram in Paris (Appendix I). The IS unit of mass is the kilogram. The abbreviation for gram is g, and for kilogram kg (1 kg = 1000 g). 

It was mentioned in Section 1-4 that the density of a substance is the mass (weight) of a unit volume of the substance in the metric system, grams per cubic centimeter or kilograms per cubic meter. 

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