Measurement Metric system

In the metric system, pressure has a unit of newtons per square meter, which is called a pascal (Pa). Although the pascal is the scientific unit and is preferred, pounds per square inch (Ibs/iif) is comnion in the United States. For example, in most of Europe, tire pressure is recorded in pascals (typically 220,000 Pa), whereas tire pressure in American cars is measured in pounds per square inch (typically 32 Ibs/in ). As a point of reference, the pressure that the earth s... 

Metric Units of Measiu ement. For the purpose of this Code, metric units of measurement are in accordance with the modernized metric system known as the International System of Units (SI). 

The resistance when moving one layer of liquid over another is the basis for the laboratory method of measuring absolute viscosity. Poise viscosity is defined as the force (pounds) per unit of area, in square inches, required to move one parallel surface at a speed of one centimeter-per-second past another parallel surface when the two surfaces are separated by a fluid film one centimeter thick. Figure 40.16. In the metric system, force is expressed in dynes and area in square centimeters. Poise is also the ratio between the shearing stress and the rate of shear of the fluid. 

Scientific measurements are expressed in the metric system. As you know, this is a decimal-based system in which all of the units of a particular quantity are related to one another by factors of 10. The more common prefixes used to express these factors are listed in Table 1.2 (page 7). 

As you can see from this discussion, a wide number of different units can be used to express measured quantities in the metric system. Ibis proliferation of units has long been of concern to scientists. In 1960 a self-consistent set of metric units was proposed. This so-called International System of Units (SI) is discussed in Appendix 1. The SI units for the four quantities discussed are... 

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 ... 

Metric system A measuring system where all units of a particular type (e.g., volume) are related to one another by powers of ten, 6-7,9 Metric ton, 7 Microstates, 453... 

Display 3-1 lists the measurements used in the metric system. The abbreviations for the measurements are given in parentiieses. 

There are three systems of measurement of drug dosages die metric system, the apothecaries system, and household measurements. The metric system is die most commonly used system of measurement in medicine A physician may prescribe a drug dosage in die apotiiecaries system, but for die most part this ancient system of measurements is only occasionally used. The household system is rarely used in a hospital setting but may be used to measure drug dosses in the home... 

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. 

Cubic Meter (m3) A measure of volume in the metric system. 

The knowledge and application of pharmaceutical and clinical calculations are essential for the practice of pharmacy and related health professions. Many calculations have been simplified by the shift from apothecary to metric system of measurements. However, a significant proportion of calculation errors occur because of simple mistakes in arithmetic. Further, the dosage forms prepared by pharmaceutical companies undergo several inspections and quality control tests. Such a luxury is almost impossible to find in a pharmacy or hospital setting. Therefore it is imperative that the health care professionals be extremely careful in performing pharmaceutical and clinical calculations. In the present chapter, a brief introduction is provided for the three systems of measurement and their interconversions ... 

The metric system, which is federally mandated and appears in the official listing of drugs in the United States Pharmacopoeia (USP), is a logically organized system of measurement. It was first developed by the French. The basic units multiplied or divided by 10 comprise the metric system. Therefore, a knowledge of decimals, reviewed in Chapter 1, is useful for this system. 

Nutritional energy values are usually measured in kilocalories (kcal or simply calories). One kilocalorie represents the amount of heat required to raise the temperature of 1 kg of water by 1°C at room temperature. In the metric system, the energy value is expressed in joules (J), with 1 kcal being equal to 4.184 kilojoules (kJ). 

The measurement system that you will most likely encounter is the SI (Metric) system. Each quantity (such as mass and volume) has a base unit and a prefix that modifies the base unit. The prefixes are the same for all quantities and are based on a decimal system. Below are some basic SI units we will introduce others in later chapters ... 

Some measures of weight and volume Metric system... 

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

Determined to bring order to the chaotic systems of measurement then used in Russia, he used techniques developed abroad and invented some measuring devices himself. He established the metric system in Russia and insisted on a greater precision in measuring equipment. 

Chemists routinely measure quantities that run the gamut from very small (the size of an atom, for example) to extremely large (such as the number of particles in one mole). Nobody, not even chemists, likes dealing with scientific notation (which we cover in Chapter 1) if they don t have to. For these reasons, chemists often use a metric system prefix (a word part that goes in front of the base unit to indicate a numerical value) in lieu of scientific notation. For example, the size of the nucleus of an atom is roughly 1 nanometer across, which is a nicer way of saying 1x10- meters across. The most useful of these prefixes are in Table 2-2. 

You measure a length to be 0.005 m. How can this be better expressed using a metric system prefix ... 

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. 

Lavoisier began to feel his own insecurity he was personally attacked in pamphlets. Gradually he withdrew from his public offices, giving his attention more completely to the work of the commission of weights and measures, then laboring with the determination of the standards of the metric system. 

Except for temperature and time, nearly all scientific measurements are based on the metric system. In recent years, there has been a concerted international effort to persuade scientists to express all metric measurements in terms ofjust seven basic units, called SI units (for Systeme International). In addition to the seven basic SI units, there are seventeen other common units derived from them that have special names. However, despite the logical arguments that have been put forth for undeviating adherence to SI units, there has not been a strong popular move in this direction. For one thing, each scientist must cope... 

Table 4-2 shows how some of the basic metric units are related to units commonly used in English-speaking countries for nonscientitle measurements. Although the United States, Great Britain, and Canada have officially resolved to convert to the metric system, it will be many years before the conversion is complete. In the meantime, you must learn to convert from one system to the other. The three conversion factors given in Table 4-2 (rounded off to 2.54... 

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