English units of length

Chemistry and physics are experimental sciences, based on measurements. Our characterization of molecules (and of everything else in the universe) rests on observable physical quantities, expressed in units that ideally would be precise, convenient and reproducible. These three requirements have always produced trade-offs. For example, the English unit of length inch was defined to be the length of three barleycorns laid end to end—a convenient and somewhat reproducible standard for an agricultural society. When the metric system was developed in the 1790s, the meter was defined to be... 

The advantages of SI will seem obvious to any student of science. Let s compare the SI units of length to the English units of length ... 

Comparing English Units of Length to SI Units of Length > ... 

Convert 3.50 yards to (a) millimeters, (b) meters. The bridge between the English units of length and the SI (metric system) is the unit factor (see Table 1-2) 1 in/2.54 cm. 

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. 

The meter is the standard unit of length (distance) in both SI and metric systems. The meter is defined as the distance light travels in a vacuum in 1/299,792,468 second. It is approximately 39.37 inches. In situations in which the English system would use inches, the metric centimeter (1/100 meter) is convenient. The relationship between inches and centimeters is shown in Figure 1-12. 

The conversion factor 2.54 cm/in. can be used to convert from an English to a metric unit of length. 

The English system is a collection of functionally unrelated units. In the English system of measurement the standard pound (lb) is the basic unit of weight. The fundamental unit of length is the standard yard (yd), and the basic unit of volume is the standard gallon (gal). The English system is used in the United States in business and industry. However, it is not used in scientific work, primarily because it is difficult to convert from one unit to another. Eor example. 

The metric system is a decimal-based system in contrast to the English system. In the metric system, mass is represented as the gram, length as the meter, and volume as the liter. Any subunit or multiple unit contains one of these units preceded by a prefix indicating the power of ten by which the base unit is to be multiplied to form the subunit or multiple unit. Scientists favor this system over the not-so-systematic English units of measurement. 

The standard metric unit of length is the meter. Large distances are measured in kilometers smaller distances are measured in millimeters or centimeters. Very small distances (on the atomic scale) are measured in nanometers (run). The standard metric unit of volume is the liter. A liter is the volume occupied by 1000 grams of water at 4 degrees Celsius. The standard metric unit of time is the second, a unit that is used in the English system as well. 

Which metric unit of length or distance is most comparable in scale to each of the following English system units for making measurements ... 

The basic unit of length in the SI system is the meter (m). A meter is a little longer than a yard there are 1.094 yards in a meter, to be exact. But that s not a really useful conversion. The most useful Sl/English conversion for length is... 

The SI base unit of length is the meter (m), a distance only slightly longer than a yard. The relations between die English and metric system units that we will use most frequently in this text appear on the back inside cover. We will discuss how to convert English units into metric units, and vice versa, in Section 1.6. 

The SI unit of length is the metre, spelled in a way that corresponds to its French pronunciation. In America, and in this book, it is written meter, which matches the English pronunciation. 

The English system of measurement has the yard as its unit of length, the pound as its unit of mass, and the second as its unit of time. 

The system of units used in chemistry is the SI system (Systeme International), which is related to the metric system. There are base units for length, mass, etc. and decimal prefixes that modify the base unit. Since most of us do not tend to think in these units, it is important to be able to convert back and forth from the English system to the SI system. These three conversions are useful ones, although knowing the others might allow you to simplify your calculations ... 

Meter a unit of measurement of length in the metric system. One meter equals approximately 39.37 inches in the English system. 

English units are based on inconsistent standards. When that medieval king s thumb became regrettably unavailable for further consultation, the standard for the inch was changed to the length of three grains of barley, placed end to end—not much of an improvement. Metric units, on the other hand, are based on defined and controlled standards, not on the whims of humans. 

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