Factors for Some Common SI Units

APPENDIX D CONVERSION FACTORS FOR SOME COMMON SI UNITS... 

Table 1.2. Conversion factors for some common SI units " (An asterisk denotes an exact relationship.)...

These relations are listed in Table 4.1 together with the conversion factors for some non-SI units still commonly in use. 

Table 1.3 gives some commonly used non-SI units for certain quantities, together with conversion factors relating them to SI units. We use these in some examples and problems, except for the calorie unit of energy. This last, however, is frequently encountered. 

In the SI system, the meter (m) and the centimeter (cm) are common units of length. An English unit, the foot (ft), still is used to some extent in fields such as hydrology and meteorology. Table A-2 gives common units of length and interconversion factors. Table A-3 presents multiplier prefixes for use with SI units. 

Pressure is force per unit area and has dimensions of [M/LT2]. Pressure is an important measurement in many fields of science, and each held has different traditional units. The SI unit, the pascal [N/m2 or kg/(m sec2)], is commonly used, along with the dyn/cm2. Other pressure units frequently encountered include the millimeter of mercury (mm Hg), the atmosphere (atm), the bar (106 dyn/cm2), and the pound per square inch (psi). The origin of some of these units is implicit in their names the millimeter of mercury (also called a torr) is the amount of pressure that causes the mercury in a manometer to rise by 1 mm—an easy unit of measure for the laboratory experimentalist to use. Many of the common units of pressure and their interconversion factors are shown in Table A-7. 

The metric system, or International System (SI, from Systlme International), is a decimal system of units for measurements of mass, length, time, and other physical quantities. Built around a set of standard units, the metric system uses factors of 10 to express larger or smaller numbers of these units. To express quantities that are larger or smaller than the standard units, prefixes are added to the names of the units. These prefixes represent multiples of 10, making the metric system a decimal system of measurements. Table 2.1 shows the names, symbols, and numerical values of the common prefixes. Some examples of the more commonly used prefixes are... 

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