Centimeter-gram-second units

In this book SI (International System of Units) units are used fairly consistently in keeping with current practice. Some quantities are traditionally expressed in hybrid units —for example, the specific area is usually measured in m2 g "1 — and we continue this practice. The older literature uses cgs (centimeter-gram-second) units almost exclusively, so the reader must be cautious in consulting other sources. Appendix B contains a list of conversion factors between SI and cgs units. 

The negative sign indicates that momentum is transferred down the velocity gradient. The proportionality constant n (Pa s) is called molecular viscosity or simply viscosity, which is an intensive property. The unit of viscosity in CGS (centimeter-gram-second) units is called poise (gcm s ). From Equation 2.4 we obtain... 

CGS is an abbreviation for centimeter-gram-second units adopted since 1874 Ref Hackh s Diet (1944), 297... 

Because this result has been obtained by solving a generalized Poisson-Boltzmann equation with the linearization approximation, it is necessary to compare it with the DLVO theory in the limit where the Debye approximation holds. In this case, Verwey and Overbeek [2], working in cgs (centimeter-gram-second) units, derived the following approximate equation for the repulsive potential ... 

The following steps illustrate calculation of shear stress and shear rate. Note that centimeter-gram-second units were used as in the original work (Vitali and Rao, 1982), but the final values are in SI units. 

Chemical Abstracts Service chlorofluorocarbon centimeter-gram-second unit system configuation interaction colour index... 

The individual processes listed within each of the coupling boxes in the P-H-C matrix of Table 1 differ in their magnitudes greatly one from another. A measure of a magnitude of a process is either a mass flux (F, in centimeter-gram-second units)... 

We may personally prefer to use the more broadly accepted MKS units, but we have to deal with the ground reality of the situation — that certain vendors (especially North American ones) still use CGS (centimeter-gram-seconds) units. Since we would certainly be evaluating and looking at their datasheets too, we will need to use the conversions in Table 2-4. 

Dyne - The absolute centimeter-gram-second unit of force that force that will impart to a free mass of one gram an acceleration of one centimeter per second per second. 

The official set of units that physicists and chemists use is the International System of Units, or SI units. The letters SI stand for Systeme Internationale, the French name for the set of units. In this system there are seven base units. The unit of length is the meter (m). The unit of mass is the kilogram (kg). The unit of time is the second (s). The unit of temperature is the kelvin (K). The unit of electric current is the ampere (A). The unit of luminous intensity is the candela (cd). The unit for the amount of a substance is the mole (mol). The SI units are called MKS (meter-kilogram-second) units. Prior to 1961, most chemists and some physicists used cgs (centimeter-gram-second) units, but we now use SI units to avoid confusion. 

A dual system of units is used in this book, with the primary system being the the International System of Units (SI units, or meter-kilogram-second units). Because of a tradition of using cgs (centimeter-gram-second) units in this field, especially in the United States, cgs imits are included in square brackets, and some equations and most examples are presented both ways. 

While the Systeme International d Unites (SI) system of units is not particularly relevant to physical chemistry and requires additional and sometimes awkward constants, its broad use deserves attention. The majority of the derivations are made in the cgs/esu (centimeter-gram-second/electrostatic unit) system of units however, both the SI and cgs systems are explained and tables for their interconversion are given in Chapters V and VI. 

Viscosity is the force in dynes required to move a plane 1 cm in area at a distance of 1 cm from another plane 1 cm in area through a distance of 1 cm in 1 s. In the centimeter-gram-second (cgs) system, the unit of viscosity is the poise (P) or centipoise (1 cP = 0.01 P). Two other terms in common use are kinematic viscosity and fluidity. The kinematic viscosity is the viscosity in centipoise divided by the specific gravity, and the unit is the stoke (cm /s), although the centistoke (0.01 st = 1 cSt) is in more common use fluidity is simply the reciprocal of viscosity. 

Zeeman displacement spect The separation, in wave numbers, of adjacent spectral lines in the normal Zeeman effect in a unit magnetic field, equal (in centimeter-gram-second Gaussian units) to e/4innc, where e and m are the charge and mass of the electron, or to approximately 4.67 x 10 (centimeter) (gauss) . za man di.splas-mant ... 

These two thin liquid films, which are also called diffusion films, diffusion layers, or Nernst films, have thicknesses that range between 10 and 10 cm (in this chapter centimeter-gram-second (CGS) units are used, since most published data on diffusion and extraction kinetics are reported in these units comparison with literature values is, therefore, straightforward). 

Viscosity is then a measure of the resistance of a material to flow. In fact, the inverse of viscosity is given the name fluidicity. A material s resistance to flow increases with its viscosity. Viscosity has been reported using a number of different names. The centimeter-gram-second (CGS) unit of viscosity is called the poise, which is a dyne seconds per square centimeter. Another widely used unit is the pascal (or Pa), which is Newton seconds per square centimeter. In fact, 1 Pa= 10 poise. 

What are the units of a poise in the centimeter-gram-second (cgs) system ... 

Density is defined as the mass of a unit volume of material at a specified temperature and has the dimensions of grams per cubic centimeter (a close approximation to grams per milliliter). Specific gravity is the ratio of the mass of a volume of the substance to the mass of the same volume of water and is dependent on two temperatures, those at which the masses of the sample and the water are measured. When the water temperature is 4°C (39°F), the specific gravity is equal to the density in the centimeter-gram-second (cgs) system, since the volume of 1 g of water at that temperature is, by definition, 1 ml. Thus the density of water, for example, varies with temperature, and its specific gravity at equal temperatures is always unity. The standard temperatures for a specific gravity in the petroleum industry in North America are 60/60°F (15.6/15.6°C). 

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. 

You might occasionally see the centimeter-gram-second (cgs) system units instead of the SI units. In the SI system, the unit of force is the newton, while in the cgs system, the unit of force is the dyne. Using this system, the unit of work is called the erg and is equal to a dyne-centimeter. Applying a force of 1 dyne over a displacement of 1 cm expends one erg of work. 

Still, units can be a nuisance. One difficulty is that much serious theoretical work is still done in centimeter-gram-second (cgs) or "Gaussian" units such is the case with the Level 3 derivations in this text. Most students learn applications in meter-kilogram-seconds (mks) "SI" or "Systeme International" units. Happily, practical formulae for... 

Given two popular systems of units, SI (= Systeme International, or rationalized MKSC, or Giorgi, or MKSA) and the older cgs (centimeter-gram-second) system, we give first two fundamental equations, Coulomb s law of 1785 and Ampere s64 law of 1826, in both systems. 

In the centimeter-gram-second (CGS) system, where the smaller units of the centimeter and gram are employed, the unit of dynamic viscosity is the poise ... 

Centimeter-gram-second this system of units has been used mostly in scientific work. 

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