SI Metric System

FIGURE 2.1 Length in the metric (SI) system is based on the meter, which is slightly longer than a yard. Cl How many centimeters are in a length of 1 inch ... 

Design a GUI that enables the user to convert from the engineering (American) to metric (SI) system of units for the following physical quantities length, mass, density, volume, force, energy, speed, and power. Refer to any standard textbook in chemical engineering to pick up the proper unit(s) in the US and SI systems and the required conversion factor from and to the SI system. 

This chapter presents two systems of units so that you can follow the examples ahead. These two systems of units are the metric SI and what is termed by the American Society of Mechanical Engineers (ASME) as the U.S. Customary system of units, namely in the ASME Section II Part D [I], This system is also termed the American Engineering System (AES) by the U.S. government. I mentioned the latter term in my book Piping and Pipelines Assessment Guide [2], in how to use the two systems of units. In this book, we will discuss briefly the other variants of the metric SI system, but it is the prevailing metric system of units. Likewise, we will concentrate on the U.S. Customary system versus the British Imperial system. Even though the latter two are similar, there are some differences. 

When you are using the metric SI system of units, it is wise to remember that many units are named in terms of a magnitude of 10, e.g., kilo or mega as a prefix. When you are performing computations, it is advised to reduce these terms to their most basic set of units. For example, if you have a cylinder that is 609.6mm (24") ID that contains 1000KPa of pressure that is 24mm thick, the hoop stress is... 

If the pressure (written in KPa) is not converted correctly to megapascals (MPa), then big errors can occur. 1 have seen this problem occur with veteran users of the metric SI systan. The error is even more likely with those not accustomed to using the metric SI system. 

The unit of toughness is a very important parameter used in fracture mechanics. Toughness, K, is the property of a material to absorb energy, hi the U.S. Customary system, this unit is expressed as ksiVin. When using the metric SI system, many people use MPa An, mainly because it is closer in value to the U.S. Customary unit. The m denotes meters. The critical value of the mode stress intensity, Kj, at which fracture occurs is a function of the maximum uniform membrane stress. In the SI system, stress is usually denoted as MPa (N/mm ). Since the stress unit MPa is 1.0 N/mm, the unit for toughness becomes... 

Note These equations are empirical and developed using U.S. Customary units. If you are using the metric SI system, it is recommended that you use the equations with U.S. Customary units and then convert them to the metric SI system. 

Units. The SI system of units and conversion factors (qv) has been formally adopted worldwide, with the exception of Bmnei, Burma, Yemen, and the United States. The participation of the United States in the metrication movement is evident by the passage of the Metric Acts of 1866 and 1975 and the subsequent estabUshment of the American National Metric Council (private) and the U.S. Metric Board (pubHc) to plan, coordinate, monitor, and encourage the conversion process. 

SI (Systeme International) The International System of units a collection of definitions of units and symbols and their deployment. It is an extension and rational ization of the metric system. See also Appendix IB. side chain A hydrocarbon substituent on a hydrocarbon chain. 

SI (Systeme International d Unites) a modern version of the metric system. significant digits significant figures. 

The "Systeme International" (S ) units, based on the metric system, were designed to achieve maximum internal consistency. The SI system is based on the following set of defined units ... 

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 ... 

SI system The system of units used in science is the SI system (Systeme International), which is related to the metric system. 

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 recent engineering research papers, units with the International System of Units (SI) are generally used. The SI system is different from the CGS system often used by scientists or from the conventional metric system used by engineers [4]. In the SI system, kilogram is used for mass only, and newton (N), which is the... 

Under an international agreement concluded in 1960, scientists throughout the world now use the International System of Units for measurement, abbreviated SI for the French Systeme Internationale d Unites. Based on the metric system, which is used in all industrialized countries of the world except the United States, the SI system has seven fundamental units (Table 1.3). These seven fundamental units, along with others derived from them, suffice for all scientific measurements. We ll look at three of the most common units in this chapter—those for mass, length, and temperature—and will discuss others as the need arises in later chapters. 

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. 

SI (Systeme International, International System of Units)—metric-based system of weights and measures adopted in 1960 by the 11th General Conference on Weights and Measures, in which 36 countries, including the U.S., participated. SI consists of seven basic units ... 

The metric system consists of a base unit and (sometimes) a prefix multiplier. Most scientists and healthcare providers use the metric system, and you are probably familiar with the common base units and prefix multipliers. The base units describe the type of quantity measured length, mass, or time. The SI system is sometimes called the MKS (meter, kilogram, second) system, because these are the standard units of length, mass, and time upon which derived quantities, such as energy, pressure, and force, are based. An older system is called the CGS (centimeter, gram, second) system. The derived CGS units are becoming extinct. Therefore, we will focus on the MKS units. 

The measures of length, volume, mass, energy, and temperature are used to evaluate our physical and chemical environment. Table 2.2 compares the metric system with the more recently accepted SI system (International System of Units). The laboratory equipment associated with obtaining these measures is also listed. 

Mass measurements of objects are carried out with the laboratory balance. Many types of balances are available for laboratory use. The proper choice of a balance depends upon what degree of accuracy is needed for a measurement. The standard units of mass are the kilogram (kg) in the SI system and the gram (g) in the metric system. Some conversion factors are listed below. 

In the literature, information is found using different systems of units metric, SI, and the English system. Quotations from the literature are presented in their original form. It would be difficult to change all these units in the book to one system. To assist the reader in converting these units, an appendix is provided with conversion factors for all units found in the text. 

The relationship between shearing stress and rate of shear can be used to define the flow properties of materials. In the simplest case, the shearing stress is directly proportional to the mean rate of shear x = fly (Figure 8-5). The proportionality constant T is called the viscosity coefficient, or dynamic viscosity, or simply the viscosity of the liquid. The metric unit of viscosity is the dyne.s cm-2, or Poise (P). The commonly used unit is 100 times smaller and called centiPoise (cP). In the SI system, t is expressed in N.s/m2. or... 

The name SI is derived from Systbme International d Unites and has evolved from an original basis of a given length (meter) and mass (kilogram) established by members of the Paris Academy of Science in the late eighteenth century. The original system was known as the metric system, but there are differences in the modem SI system and the old metric system based primarily on new names being added for derived terms. 

Units. Labels which distinguish one type of measurable quantity from other types. Length, mass and time are distinctly different physical quantities, and therefore have different unit names, meters, kilograms and seconds. We use several systems of units, including the metric (SI) units, the English (orU.S. customary units), and a number of others of mainly historical interest. 

For some readers (especially Americans), the metric system (other wise known as the SI system) is vague, or somewhat unfamiliar. 99% of all the units of weight and measurement in this book are given using the SI system therefore, a translation from one unit to another may be needed for some to fully interpret the quantities. As most people are probably aware however, most laboratory equipment is automatically calibrated in SI units, so even inexperienced persons will not have to worry too much about knowing the SI system. Regardless, try a few conversions of your own just for practice. Example Convert 150 Celsius into Fahrenheit—Solution multiply 150 by 1.8 and then add 32. The answer would be 302 Fahrenheit. Example 2 Convert 1.2 gallons into milliliters—Solution multiply 1.2 by 3,785. The answer would be 4542 milliliters. 

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