Guide for the Use of the International System of Units (SI)
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Appendix A: Symbols and Prefixes
Appendix A: Symbols and Prefixes (Appendix A last revised November 2020) This appendix of the Author's Kit provides recommendations on prefixes, unit symbols and abbreviations, and factors for conversion into units of the International System. Prefixes Recommended prefixes indicating decimal multiples or submultiples of units and their symbols are as follows: Multiple Prefix Abbreviation 1024 yotta Y 1021 zetta Z 1018 exa E 1015 peta P 1012 tera T 109 giga G 106 mega M 103 kilo k 102 hecto h 10 deka da 10-1 deci d 10-2 centi c 10-3 milli m 10-6 micro μ 10-9 nano n 10-12 pico p 10-15 femto f 10-18 atto a 10-21 zepto z 10-24 yocto y Avoid using compound prefixes, such as micromicro for pico and kilomega for giga. The abbreviation of a prefix is considered to be combined with the abbreviation/symbol to which it is directly attached, forming with it a new unit symbol, which can be raised to a positive or negative power and which can be combined with other unit abbreviations/symbols to form abbreviations/symbols for compound units. For example: 1 cm3 = (10-2 m)3 = 10-6 m3 1 μs-1 = (10-6 s)-1 = 106 s-1 1 mm2/s = (10-3 m)2/s = 10-6 m2/s Abbreviations and Symbols Whenever possible, avoid using abbreviations and symbols in paragraph text; however, when it is deemed necessary to use such, define all but the most common at first use. The following is a recommended list of abbreviations/symbols for some important units. -
Quantity Symbol Value One Astronomical Unit 1 AU 1.50 × 10
Quantity Symbol Value One Astronomical Unit 1 AU 1:50 × 1011 m Speed of Light c 3:0 × 108 m=s One parsec 1 pc 3.26 Light Years One year 1 y ' π × 107 s One Light Year 1 ly 9:5 × 1015 m 6 Radius of Earth RE 6:4 × 10 m Radius of Sun R 6:95 × 108 m Gravitational Constant G 6:67 × 10−11m3=(kg s3) Part I. 1. Describe qualitatively the funny way that the planets move in the sky relative to the stars. Give a qualitative explanation as to why they move this way. 2. Draw a set of pictures approximately to scale showing the sun, the earth, the moon, α-centauri, and the milky way and the spacing between these objects. Give an ap- proximate size for all the objects you draw (for example example next to the moon put Rmoon ∼ 1700 km) and the distances between the objects that you draw. Indicate many times is one picture magnified relative to another. Important: More important than the size of these objects is the relative distance between these objects. Thus for instance you may wish to show the sun and the earth on the same graph, with the circles for the sun and the earth having the correct ratios relative to to the spacing between the sun and the earth. 3. A common unit of distance in Astronomy is a parsec. 1 pc ' 3:1 × 1016m ' 3:3 ly (a) Explain how such a curious unit of measure came to be defined. Why is it called parsec? (b) What is the distance to the nearest stars and how was this distance measured? 4. -
Representation of Derived Units in Unitsml (Revised December 8, 2006)
Representation of Derived Units in UnitsML (revised December 8, 2006) Peter J. Linstrom∗ December 8, 2006 ∗phone: (301) 975-5422,DRAFT e-mail: [email protected] 1 INTRODUCTION 12/8/06 Contents 1 Introduction 1 2 Why this convention is needed 2 3 Information needed to define a unit 3 4 Proposed XML encoding 4 5 Important conventions 7 6 Potential problems 8 7 Possible alternatives 10 A Multiplicative prefixes 12 B SI units and units acceptable for use with the SI 14 C non-SI Units 19 1 Introduction This document describes a proposed convention for defining derived units in terms of their base units. This convention is intended for use in the UnitsML markup language to allow a precise definition of a wide range of units. The goal of this convention is to improve interoperability among applications and databases which use derived units based on commonly encountered base units. It is understoodDRAFT that not all units can be represented using this convention. It is, however, Representation of Derived Units in UnitsML (revised December 8, 2006) Page 1 2 WHY THIS CONVENTION IS NEEDED 12/8/06 anticipated that a wide range of scientific and engineering units of measure can be represented with this convention. The convention consists of representing the unit in terms of multiplicative combinations of base units. For example the unit centimeter per second squared would be represented in terms of the following: 1. The unit meter with the prefix centi raised to the power 1. 2. The unit second raised to the power −2. -
Astm Metric Practice Guide
National Bureau of Standards Library, E-01 Admrn. Bldg. A111DO cmfl4S - m 2 0 1967 METRIC PRACTICE GUIDE NATL INST OF STANDARDS & TECH R.I.C. All100991845 /NBS handbook QC1 .U51 V102;1967 C.1 NBS-PUB-C 1934 U. S. DEPARTMENT OF COMMERCE NATIONAL OUREAU OF STANDARDS HANDBOOK 102 THE NATIONAL BUREAU OF STANDARDS The National Bureau of Standards 1 provides measurement and technical information services essential to the efficiency and effectiveness of the work of the Nation’s scientists and engineers. The Bureau serves also as a focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To accomplish this mission, the Bureau is organized into three institutes covering broad program areas of research and services: THE INSTITUTE FOR BASIC STANDARDS . provides the central basis within the United States for a complete and consistent system of physical measurements, coordinates that system with the measurement systems of other nations, and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation’s scientific com¬ munity, industry, and commerce. This Institute comprises a series of divisions, each serving a classical subject matter area: —Applied Mathematics — Electricity—Metrology — Mechanics — Heat — Atomic Physics—Physical Chemistry—Radiation Physics—Laboratory Astrophysics2—Radio Standards Laboratory,2 which includes Radio Standards Physics and Radio Standards Engineering—Office of Standard Reference Data. THE INSTITUTE FOR MATERIALS RESEARCH . conducts materials research and provides associated materials services including mainly reference materials and data on the properties of materials. Beyond its direct interest to the Nation’s scientists and engineers, this Institute yields services which are essential to the advancement of technology in industry and commerce. -
Frequently Asked Questions Coins and Notes July 2020
Frequently Asked Questions Coins and Notes July 2020 A. Currency Issuance 1. Under what authority does the Bangko Sentral ng Pilipinas (BSP) issue currency? The BSP is the sole government institution mandated by law to issue notes and coins for circulation in the Philippines. In Particular, Section 50 of Republic Act (R.A) No. 7653, otherwise known as The New Central Bank Act, as amended by Republic Act No. 11211, stipulates that the BSP shall have the sole power and authority to issue currency within the territory of the Philippines. It also issues legal tender commemorative notes and coins. 2. How does the BSP determine the volume/value of notes and coins to be issued annually? The annual volume/value of currency to be issue is projected based on currency demand that is estimated from a set of economic indicators which generally measure the country’s economic activity. Other variables considered in estimating currency order include: required currency reserves, unfit notes for replacement, and beginning inventory balance. The total amount of banknotes and coins that the BSP may issue should not exceed the total assets of the BSP. 3. How is currency issued to the public? Based on forecast of currency demand, denominational order of banknotes and coins is submitted to the Currency Production Sub-Sector (CPSS) for production of banknotes and coins. The CPSS delivers new BSP banknotes and coins to the Cash Department (CD) and the Regional Operations Sub-Sector (ROSS). In turn, CD services withdrawals of notes and coins of banks in the regions through its 22 Regional Offices/Branches. -
Units, Conversations, and Scaling Giving Numbers Meaning and Context Author: Meagan White; Sean S
Units, Conversations, and Scaling Giving numbers meaning and context Author: Meagan White; Sean S. Lindsay Version 1.3 created August 2019 Learning Goals In this lab, students will • Learn about the metric system • Learn about the units used in science and astronomy • Learn about the units used to measure angles • Learn the two sky coordinate systems used by astronomers • Learn how to perform unit conversions • Learn how to use a spreadsheet for repeated calculations • Measure lengths to collect data used in next week’s lab: Scienctific Measurement Materials • Calculator • Microsoft Excel • String as a crude length measurement tool Pre-lab Questions 1. What is the celestial analog of latitude and longitude? 2. What quantity do the following metric prefixes indicate: Giga-, Mega-, kilo-, centi-, milli-, µicro-, and nano? 3. How many degrees is a Right Ascension “hour”; How many degrees are in an arcmin? Arcsec? 4. Use the “train-track” method to convert 20 ft to inches. 1. Background In any science class, including astronomy, there are important skills and concepts that students will need to use and understand before engaging in experiments and other lab exercises. A broad list of fundamental skills developed in today’s exercise includes: • Scientific units used throughout the international science community, as well as units specific to astronomy. • Unit conversion methods to convert between units for calculations, communication, and conceptualization. • Angular measurements and their use in astronomy. How they are measured, and the angular measurements specific to astronomy. This is important for astronomers coordinate systems, i.e., equatorial coordinates on the celestial sphere. • Familiarity with spreadsheet programs, such as Microsoft Excel, Google Sheets, or OpenOffice. -
Ffontiau Cymraeg
This publication is available in other languages and formats on request. Mae'r cyhoeddiad hwn ar gael mewn ieithoedd a fformatau eraill ar gais. [email protected] www.caerphilly.gov.uk/equalities How to type Accented Characters This guidance document has been produced to provide practical help when typing letters or circulars, or when designing posters or flyers so that getting accents on various letters when typing is made easier. The guide should be used alongside the Council’s Guidance on Equalities in Designing and Printing. Please note this is for PCs only and will not work on Macs. Firstly, on your keyboard make sure the Num Lock is switched on, or the codes shown in this document won’t work (this button is found above the numeric keypad on the right of your keyboard). By pressing the ALT key (to the left of the space bar), holding it down and then entering a certain sequence of numbers on the numeric keypad, it's very easy to get almost any accented character you want. For example, to get the letter “ô”, press and hold the ALT key, type in the code 0 2 4 4, then release the ALT key. The number sequences shown from page 3 onwards work in most fonts in order to get an accent over “a, e, i, o, u”, the vowels in the English alphabet. In other languages, for example in French, the letter "c" can be accented and in Spanish, "n" can be accented too. Many other languages have accents on consonants as well as vowels. -
Electric Units and Standards
DEPARTMENT OF COMMERCE OF THE Bureau of Standards S. W. STRATTON, Director No. 60 ELECTRIC UNITS AND STANDARDS list Edition 1 Issued September 25. 1916 WASHINGTON GOVERNMENT PRINTING OFFICE DEPARTMENT OF COMMERCE Circular OF THE Bureau of Standards S. W. STRATTON, Director No. 60 ELECTRIC UNITS AND STANDARDS [1st Edition] Issued September 25, 1916 WASHINGTON GOVERNMENT PRINTING OFFICE 1916 ADDITIONAL COPIES OF THIS PUBLICATION MAY BE PROCURED FROM THE SUPERINTENDENT OF DOCUMENTS GOVERNMENT PRINTING OFFICE WASHINGTON, D. C. AT 15 CENTS PER COPY A complete list of the Bureau’s publications may be obtained free of charge on application to the Bureau of Standards, Washington, D. C. ELECTRIC UNITS AND STANDARDS CONTENTS Page I. The systems of units 4 1. Units and standards in general 4 2. The electrostatic and electromagnetic systems 8 () The numerically different systems of units 12 () Gaussian systems, and ratios of the units 13 “ ’ (c) Practical ’ electromagnetic units 15 3. The international electric units 16 II. Evolution of present system of concrete standards 18 1. Early electric standards 18 2. Basis of present laws 22 3. Progress since 1893 24 III. Units and standards of the principal electric quantities 29 1. Resistance 29 () International ohm 29 Definition 29 Mercury standards 30 Secondary standards 31 () Resistance standards in practice 31 (c) Absolute ohm 32 2. Current 33 (a) International ampere 33 Definition 34 The silver voltameter 35 ( b ) Resistance standards used in current measurement 36 (c) Absolute ampere 37 3. Electromotive force 38 (a) International volt 38 Definition 39 Weston normal cell 39 (b) Portable Weston cells 41 (c) Absolute and semiabsolute volt 42 4. -
About SI Units
Units SI units: International system of units (French: “SI” means “Système Internationale”) The seven SI base units are: Mass: kg Defined by the prototype “standard kilogram” located in Paris. The standard kilogram is made of Pt metal. Length: m Originally defined by the prototype “standard meter” located in Paris. Then defined as 1,650,763.73 wavelengths of the orange-red radiation of Krypton86 under certain specified conditions. (Official definition: The distance traveled by light in vacuum during a time interval of 1 / 299 792 458 of a second) Time: s The second is defined as the duration of a certain number of oscillations of radiation coming from Cs atoms. (Official definition: The second is the duration of 9,192,631,770 periods of the radiation of the hyperfine- level transition of the ground state of the Cs133 atom) Current: A Defined as the current that causes a certain force between two parallel wires. (Official definition: The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 × 10-7 Newton per meter of length. Temperature: K One percent of the temperature difference between boiling point and freezing point of water. (Official definition: The Kelvin, unit of thermodynamic temperature, is the fraction 1 / 273.16 of the thermodynamic temperature of the triple point of water. Amount of substance: mol The amount of a substance that contains Avogadro’s number NAvo = 6.0221 × 1023 of atoms or molecules. -
Part 1: Introduction to The
PREVIEW OF THE IPA HANDBOOK Handbook of the International Phonetic Association: A guide to the use of the International Phonetic Alphabet PARTI Introduction to the IPA 1. What is the International Phonetic Alphabet? The aim of the International Phonetic Association is to promote the scientific study of phonetics and the various practical applications of that science. For both these it is necessary to have a consistent way of representing the sounds of language in written form. From its foundation in 1886 the Association has been concerned to develop a system of notation which would be convenient to use, but comprehensive enough to cope with the wide variety of sounds found in the languages of the world; and to encourage the use of thjs notation as widely as possible among those concerned with language. The system is generally known as the International Phonetic Alphabet. Both the Association and its Alphabet are widely referred to by the abbreviation IPA, but here 'IPA' will be used only for the Alphabet. The IPA is based on the Roman alphabet, which has the advantage of being widely familiar, but also includes letters and additional symbols from a variety of other sources. These additions are necessary because the variety of sounds in languages is much greater than the number of letters in the Roman alphabet. The use of sequences of phonetic symbols to represent speech is known as transcription. The IPA can be used for many different purposes. For instance, it can be used as a way to show pronunciation in a dictionary, to record a language in linguistic fieldwork, to form the basis of a writing system for a language, or to annotate acoustic and other displays in the analysis of speech. -
Distances in the Solar System Are Often Measured in Astronomical Units (AU). One Astronomical Unit Is Defined As the Distance from Earth to the Sun
Distances in the solar system are often measured in astronomical units (AU). One astronomical unit is defined as the distance from Earth to the Sun. 1 AU equals about 150 million km (93 million miles). Table below shows the distance from the Sun to each planet in AU. The table shows how long it takes each planet to spin on its axis. It also shows how long it takes each planet to complete an orbit. Notice how slowly Venus rotates! A day on Venus is actually longer than a year on Venus! Distances to the Planets and Properties of Orbits Relative to Earth's Orbit Average Distance Length of Day (In Earth Length of Year (In Earth Planet from Sun (AU) Days) Years) Mercury 0.39 AU 56.84 days 0.24 years Venus 0.72 243.02 0.62 Earth 1.00 1.00 1.00 Mars 1.52 1.03 1.88 Jupiter 5.20 0.41 11.86 Saturn 9.54 0.43 29.46 Uranus 19.22 0.72 84.01 Neptune 30.06 0.67 164.8 The Role of Gravity Planets are held in their orbits by the force of gravity. What would happen without gravity? Imagine that you are swinging a ball on a string in a circular motion. Now let go of the string. The ball will fly away from you in a straight line. It was the string pulling on the ball that kept the ball moving in a circle. The motion of a planet is very similar to the ball on a strong. -
2.1.3 Amount of Substance the Mole Is the Key Concept for Chemical Calculations
2.1.3 Amount of substance The mole is the key concept for chemical calculations DEFINITION: The mole is the amount of substance in grams that has the same number of particles as there are atoms in 12 grams of carbon-12. DEFINITION: Relative atomic mass is the average mass of one atom compared to one twelfth of the mass of one atom of carbon-12 DEFINITION: Molar Mass is the mass in grams of 1 mole of a substance and is given the unit of g mol-1 Molar Mass for a compound can be calculated by adding up the mass numbers(from the periodic table) of each element in the compound eg CaCO3 = 40.1 + 12.0 +16.0 x3 = 100.1 molar gas volume (gas volume per mole, units dm3 mol–1) . This is the volume of 1 mole of a gas at a given temperature and pressure. All gases have this same volume. At room pressure (1atm) and room temperature 25oC the molar gas volume is 24 dm3 mol–1 Avogadro's Constant There are 6.02 x 1023 atoms in 12 grams of carbon-12. Therefore explained in simpler terms 'One mole of any specified entity contains 6.02 x 1023 of that entity': 1 mole of copper atoms will contain 6.02 x 1023 atoms Avogadro's Constant can be 1 mole of carbon dioxide molecules will contain 6.02 x 1023 molecules used for atoms, molecules and 1 mole of sodium ions will contain 6.02 x 1023 ions ions For pure solids, liquids and gases Example 1: What is the amount, in mol, in 35.0g of CuSO4? amount = mass amount = mass/Mr Mr = 35/ (63.5 + 32 +16 x4) Unit of Mass: grams = 0.219 mol Unit of amount : mol Many questions will involve changes of units 1000 mg =1g 1000 g =1kg 1000kg = 1 tonne Significant Figures Give your answers to the same number of significant figures as the Example 2: What is the amount, in mol, in 75.0mg of number of significant figures for the CaSO4.2H2O? data you given in a question.