Fundamental unit

In addition to fundamental units from the SI system, i.e., m, kg, s, mol, K, A, and cd, multiples and sub-multiples of these units as well as derived or combined units are also used and indicated in parentheses. 

It is the most corrosion-resistant metal known, and was used in making the standard meter bar of Paris, which is a 90 percent platinum and 10 percent iridium alloy. This meter bar was replaced in 1960 as a fundamental unit of length (see under Krypton). 

Measurements usually consist of a unit and a number expressing the quantity of that unit. Unfortunately, many different units may be used to express the same physical measurement. For example, the mass of a sample weighing 1.5 g also may be expressed as 0.0033 lb or 0.053 oz. For consistency, and to avoid confusion, scientists use a common set of fundamental units, several of which are listed in Table 2.1. These units are called SI units after the Systeme International d Unites. Other measurements are defined using these fundamental SI units. For example, we measure the quantity of heat produced during a chemical reaction in joules, (J), where... 

The information needed to reproduce and support an animate species is given by the order in which the nitrogen bases occur along the DNA or RNA chains (-C-T-T-A-G-, for example). A sequence of three such bases (a codon) provides the fundamental unit of information. 

The general problem is posed as finding the minimum number of variables necessary to define the relationship between n variables. Let (( i) represent a set of fundamental units, hke length, time, force, and so on. Let [Pj represent the dimensions of a physical quantity Pj there are n physical quantities. Then form the matrix Ot) ... 

An example of research in the micromechanics of shock compression of solids is the study of rate-dependent plasticity and its relationship to crystal structure, crystal orientation, and the fundamental unit of plasticity, the dislocation. The majority of data on high-rate plastic flow in shock-compressed solids is in the form of ... 

The fundamental unit of tertiary structure is the domain. A domain is defined as a polypeptide chain or a part of a polypeptide chain that can fold independently into a stable tertiary structure. Domains are also units of function. Often, the different domains of a protein are associated with different functions. For example, in the lambda repressor protein, discussed in Chapter 8, one domain at the N-terminus of the polypeptide chain binds DNA, while a second domain at the C-terminus contains a site necessary for the dimerization of two polypeptide chains to form the dimeric repressor molecule. 

Finally, the fundamental unit of concentration obtained by RBS is in atoms/cm or concentration in the sample-versus-bachscattering energy loss. To convert the profile of a backscattering peak into a depth profile it is necessary to assume a density for the material being profiled. For single-element films, such as Si, Ti, and W, an elemental density can be assumed for the film and an accurate thickness is obtained. In the case of multi-elemental films with an unknown density, a density for the film is calculated by summing the density of each element, normalized to its concentration. The accuracy of this assumption is usually within 25%, but for some cases the actual density of the film may vary by as much as 50%— 100% from the assumed density. It is useful to note that ... 

Filtration is a fundamental unit operation that, within the context of this volume, separates suspended particle matter from water. Although industrial applications of this operation vary significantly, all filtration equipment operate by passing the solution or suspension through a porous membrane or medium, upon which the solid particles are retained on the medium s surface or within the pores of the medium, while the fluid, referred to as the filtrate, passes through. 

It is usual these days to express all physical quantities in the system of units referred to as the Systeme International, SI for short. The International Unions of Pure and Applied Physics, and of Pure and Applied Chemistry both recommend SI units. The units are based on the metre, kilogram, second and the ampere as the fundamental units of length, mass, time and electric current. (There are three other fundamental units in SI, the kelvin, mole and candela which are the units of thermodynamic temperature, amount of substance and luminous intensity, respectively.)... 

Electric current, 78 Electric dipoles, see Dipoles Electric discharge, 239 Electric force, 76, 77 Electricity, fundamental unit, 241 Electrochemical cell chemistry of, 199 and Le Chatelier s Principle. 214 operation, 206 standard half cell, 21C Electrodes, 207 Electrolysis, 220, 221 apparatus, 40 cells, 238 of water, 40, 115 Electrolytes, 169, 179 strong, 180 weak,180... 

For scientific purposes the convenient unit to employ for measuring reasonably large volumes of liquids is the cubic decimetre (dm3), or, for smaller volumes, the cubic centimetre (cm3). For many years the fundamental unit employed was the litre, based upon the volume occupied by one kilogram of water at 4 °C (the temperature of maximum density of water) the relationship between the litre... 

Application of dimensional analysis to Equation (8) using a set of fundamental units containing heat, mass, length, time, and temperature, yields... 

The three fundamental units of the SI and of the cgs systems are length, mass, and time. It has been shown that force can be regarded as having the dimensions of MLT-2, and the dimensions of many other parameters may be worked out in terms of the basic MLT system. For example ... 

Conversion of units from one system to another is simply carried out if the quantities are expressed in terms of the fundamental units of mass, length, time, temperature. Typical conversion factors for the British and metric systems are ... 

It may be noied that both temperature and heat are taken as fundamental units as heat... 

Fryer, P.J. 210,229 Fuller, E. N. 584,655 Fully developed flow 61.681 Fundamental units, choice of 12 Further reading, flow and pressure measurement (Chapter 6) 272... 

This exact relation defines the caloric in terms of the joule the joule is the fundamental unit. 

Using the values a0 = 13.82 A and density = 2.89 g/cm2, the numbers of atoms contained in a fundamental unit (one-fourth of the unit cube) given in Table II are calculated from published analyses. Of these analyses greatest weight can probably be laid on No. 1, 2, and 3 No. 6 is probably untrustworthy (very high sum). 

The fundamental unit of a chemical substance is called an atom. The word is derived from the Greek atomos, meaning uncuttable. An atom is the smallest possible particle of a substance. 

The fundamental unit of electrical charge is the coulomb (C), defined as the quantity of electricity transferred by a current of 1... 

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