English Systems of Measurement

The density of a substance is its weight per unit of volume. The unit of volume in the English system of measurement is 1 cubic foot or 1 f. To find the density of a substance, you must know its weight and volume. You then divide its weight by its volume to find the weight per unit volume. 

Whenever we measure something, from the weight of a sack of potatoes to the distance to the moon, we must express the result as a number of specific units for example, pounds and miles in the English system of measurement (although even England no longer fully uses that system), or kilograms and kilometers in the metric system. As of 1994, every nation in the world had adopted some aspects of the metric system, with only four exceptions the United States, Brunei, Burma, and Yemen. 

Although scientists rarely use the centuries old English system of measurement, it is still commonly used in the United States to describe quantities in everyday life. Figure... 

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 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. 

English language and the conventional American system of measurement shall be used throughout all document and tagging. 

All systems of measurement / V I are based on arbitrary standards. The SI system is as arbitrary as the English system, but the relationship of one unit to another is more systematic and easier to remember in the metric system. 

Reports on the thermochemistry of propints are numerous but widely scattered. The distinction between gun propints and rocket propints must here be kept in mind. The use of the English units of measurement is still firmly entrenched, but as the impact of a change to the SI system on the numerical values will be slight, this change is to be expected soon... 

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. ... 

In a chemistry laboratory, the metric system of measurement is used rather than the more familiar English system. The most common measurement unit for mass is the gram, not the pound. The most common measurement unit for volume is the milliliter, not the cup. One milliliter of water is a little more than half a tablespoon of water. One milliliter (abbreviated mL ) of water weighs approximately one gram (abbreviated g ). 

The metric system is a system of measurement using units based on the decimal system. Today, in English, it is formally called the International System, abbreviated SI from the original French, Systtme International. The base units of the modern metric system used in general chemistry are given in the following table. From these, you can derive all other units of measure. 

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. 

Engineering is about real physical things, which can be measured and described in terms of the units of measure. Most engineering calculations involve these units of measure. It would be simple if there were only one set of such units that the whole world agreed on and used, but that is not the case today. In the United States, most measurements use the English system of units, based on the foot, pound, and degree Fahrenheit, but most of the world uses the metric... 

Often the data to be used in a computer program are provided in actual physical units based on the SI or English thermodynamic systems of measurement. Most programs require the data in a per unit format. Care needs to be taken in converting the data into a suitable per unit format, especially the constants, scaling factors and controller limits. Figures 2.16 and 2.17 have therefore been drawn using per unit quantities. 

OBJECTIVE To learn the English, metric, and SI systems of measurement. 

The metric system, developed in France during the late eighteenth century, is used as the system of measurement in most countries. The United States has traditionally used the English system, although use of the metric system has become more common (<4 FIGURE 1.15). 

Engineers must be able to use both English units of measure and the metric system. In nanotechnology, engineers... 

The measurement system that uses such familiar units as feet, yards, ounces, pounds, and gallons is known as the English system. Another system of measurement, the metric system, will be en5>hasized in this chapter and subsequent chapters. The metric system of measurement is used almost exclusively in all... 

Avoirdupois is a French word, meaning to weigh. The old English system of weights and measures is referred to as the Avoirdupois System, or U.S. Customary Weights and Measures, to differentiate it from the Metric System. 

This quantity may also be calculated using metric units. However, the values so obtained cannot be compared with those obtained using English units because the ratios of the height to weight units differ between the two systems of measurement. The ponderal index has the applications that follow ... 

In one English system of units, lengths are measured in feet, masses are measured in pounds, abbreviated lb (1 lb = 0.4536 kg), and time is measured in seconds. The absolute temperature scale is the Rankine scale, such that 1.8° R corresponds to 1°C and to 1K. 

There are many systems of measurement in use throughout the world, but primarily two that have been in use for years— the English system and the metric system. These systems suffer from many variations and problems. 

The unit of land measure in the English system is the acre, while that in the metric system is the hectare. An acre is 4.356 X 104 ft2. A hectare is ten thousand square meters. The town of Willington in Connecticut requires a minimum area of 2.0 acres of land for a single-family dwelling. How many hectares are required ... 

Sometimes it is necessary to convert from a measurement in the English system to a measurement in the SI system. (The English system is sometimes referred to as the U.S. Customary system of units.) There are numerous SI/English conversions. Consult your book and check with your instructor to see which they recommend. We will be using the following in many of our examples ... 

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

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