Newnes Physical Science. Pocket Book for Engineers PDF
Preview Newnes Physical Science. Pocket Book for Engineers
Newnes Physical Science Pocket Book for engineers J O Bird Bsc (Hons), AFIMA, TEng (CEI), MiElecIE Ρ J CSiivers BSc (Hons), PhD Newnes Technical Books Newnes Technical Books is an imprint of the Butterworth Group which has principal offices in London, Boston, Durban, Singapore, Sydney, Toronto, Wellington First published 1983 © Butterworth and Co (Publishers) Ltd, 1983 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including photocopy ing and recording without the written permission of the copyright holder, application for which should be addressed to the publishers. Such written permission must also be obtained before any part of this publicadon is stored in a retrieval system of any nature. This book is sold subject to the Standard Condidons of Sale of Net Books and may not be resold in the UK below the net price given by the Publishers in their current price list. British Library Cataloguing in Publication Data Bird, J. O. Newnes physical science pocket book. 1. Science L Title Π. Chivers, P. J. 500.2 ai58.5 ISBN 0-408-01343-5 Typeset by Mid-County Press Printed in England by The Thetford Press Ltd, Thetford, Norfolk Preface This Physical Science pocket book is intended to provide students, technicians, scientists and engineers with a readily available reference to the essential physical sciences formulae, definitions and general information needed during their studies and/or work situation. The book is divided, for convenience of reference, into four sections embracing general science, physics, electrical science and chemistry. The text assumes little previous knowledge and is suitable for a wide range of courses. It will be particularly useful for students studying for Technician certificates and diplomas, and for CSE and Ό' and *A' levels. The authors would like to express their appreciation for the friendly co-operation and helpful advice given to them by the publishers and by the editor, Tony May. Thanks are also due to Simon Pascoe for his agreeing to use of some material from Physics 2 Checkbook, and to Mrs Elaine Woolley and Mrs Sandra Chivers foi the excellent typing of the manuscript. Finally the authors would like to add a word of thanks to their wives, Elizabeth and Sandra for their patience, help and encouragement during the preparation of this book. J O Bird and Ρ J Chivers Highbury College of Technology Portsmouth 1 SI units 1 The systems of units used in engineering and science is the Systéme bitematíoiiale donates (International system of units), usually abbreviated to SI units, and is based on the metric system. This was introduced in 1960 and is now adopted by the majority of countries as the official system of measurement. 2 The basic units in the SI system are given in Table 1.1. Table 1.1 Quantity Unit length metre, m mass kilogram, kg time second, s electric current ampere, A thermodynamic temperature kelvin, Κ luminous intensity candela, cd amount of substance mole, mol SI units may be made larger or smaller by using prefixes which denote multiplication or division by a particular amount. The eight most common multiples, with their meaning, are listed in Table 1.2. Table 1.2 Prefix Name Meaning Τ te ra multiply by 1 000000000000 (i.e. χ 10^^^ G gig a multiply by 1 000000000 (i.e. χ 10^) Μ mega multiply by 1 000000 (i.e. «10^) k kilo multiply by 1 000 (i.e. 10^) m milli divide by 1 000 (i.e. χ 10"3) μ micro divide by 1 000000 (i.e. χ 10"^) η nano divide by 1 000000000 (i.e. χ 10"^) Ρ pico divide by 1 000000000000 (i.e. χ 10" 4 (i) Length is the distance between two points. The standard unit of lengdi is the metre, although the centimetre, cm, millimetre, mm and kilometre, km, are often used. 1 cm= 10 mm; 1 m = 100 cm = 1000 mm; 1 km = 1000 m. (ii) Area is a measure of the size or extent of a plane surface and is measured by multiplying a length by a length. If the lengths are in metres then the unit of area is the square metre, m^. 1 m^=l mxl m = 100 cm χ 100 cm = 10000 cm^ or 10^ cm2 = 1000 mm X 1000 mm = 1000000 mm^ or 10^ mm^ Conversely, 1 cm^ = 10""^ m^ and 1 mm^ = 10"^ m^. (iii) Volume is a measure of the space occupied by a solid and is measured by multiplying a length by a length by a length. If the lengths are in metres then the unit of volume is in cubic metres, m^. 1 m^ = l mxl mxl m=100cmxl00cmxl00cm = 106cm3 = 1000 mm χ 1000 mm χ 1000 mm = 10^ mm^ Cbnvereely, 1 cm^= 10"^ m^ and 1 mm3= 10"^ m^ Another unit used to measure volume, particularly with liquids, is the litre (1) where 1 litre = lOiOO cm^. (iv) Mass is the amount of matter in a body and is measured in kilograms, kg. 1 kg = 1000 g (or conversely, 1 g= 10"^ kg) and 1 tonne (t) = 1000kg. 5 Derived SI units use combinations of basic units and there are many of them. Two examples are: velocity metres per second, (m/s) acceleration metres per second square, (m/s^). (a) The unit of diarge is the coulomb, (C), where one coulomb is one ampere second. (1 coulomb = 6.24 χ lO'^ electrons). The coulomb is defined as the quantity of electricity which flows past a given point in an electric circuit when a current of one ampere is maintained for one second. Thus chaiige in coulombs, Q^Ít where / is the current in amperes and / is the time in seconds. (b) The unit offeree is the newton, (N), where one newton is one kilogram metre per second squared. The newton is defined as the force which, when applied to a mass of one kilogram, gives it an acceleration of one metre per second squared. Thus force in newtons, F=me, where m is the mass in kilograms and a is the acceleration in metres per second squared. Gravitational force, or weight, is mgy where ^ = 9.81 m/s^. (c) The unit of work or energy is the joule, J), where one joule is one newton metre. The joule is defined as the work done or energy transferred when a force of one newton is exerted through a distance of one metre in the direction of the force. Thus work done on a body in joules, fV= Fs, where F is the force in newtons and s is the distance in metres moved by the body in the direction of the force. Energy is the capacity for doing work. (d) (i) The unit of power is the watt, (W), where one watt is one joule per second. Power is defined as the rate of doing work or transferring energy. Thus: power m watts, ^=~' where W is the work done or energy transferred in joules and / is the time in seconds. Hence, energy in joules, W = PL (e) The unit of electric potential is the volt (V) where one volt is one joule per coulomb. One volt is defined as the diflerence in potential between two points in a conductor which, when carrying a current of one ampere dissipates a power of one watt. ( watts joules/second joules i.e. volts = = = amperes amperes ampere seconds joules coulomb J A change in electric potential between two points in an electric circuit is called a potential difference. The electromotive force (e.m.f.) provided by a source of energy such as a battery or a generator is measured in volts. 2 Density (i) Density is the mass per unit volume of a substance. The symbol used for density is ρ (Greek letter rho) and its units are kg/m^. m Density = I.e., P= — volame V m m = pV V= — L Ρ where m is the mass in kg, V is the volume in m^ and ρ is the density in kg/m^. (ii) Some typical values of densities include: aluminium 2 700 kg/m^ copper 8900 kg/m^ lead 11 400 kg/m^ cast iron 7 000 kg/m^ steel 7 800 kg/m^, water 1 000 kg/m^ cork 250 kg/m^, petrol 700 kg/ml (i) The relative density of a substance is the ratio of the density of the substance to the density of water. density of substance i.e. relative density = density of water Relative density has no units, since it is the ratio of two similar quantities. (ii) Typical values of relative densities can be determined from para. 1, (since water has a density of 1000 kg/m^, and include: aluminium 2.7, copper 8.9, lead 11.4, cast iron 7.0, steel 7.8, cork 0.25, petrol 0.7. (iii) The relative density of a liquid (formerly called the 'specific gravity') may be measured using a hydrometer. 3 Scalar and vector quantities Quantities used in engineering and science can be divided into two groups: (a) Scalar quantitiee have a size or magnitude only and need no other information to specify them. Thus, 10 cm, 50 sec, 7 litres and 3 kg are all examples of scalar quantities. (b) Vector qnantitiee have both a size or magnitude and a direction, called the line of action of the quantity. Thus, a velocity of 50 km/h due east, on acceleration of 9.8 m/s^ vertically downwards and a force of 15 Ν at an angle of 30° are all examples of vector quantities. 4 Standard quantity symbols and units Quantity ^antity symbol Unit Unit symbol Acceleration: gravitational g metres per second m/s2 squared linear a metres per second mm//ss22 squared Angular α radians per rraadd//ss22 acceleration second squared Angular velocity ω radians per rad/s second Area A square metres m2 Area, second I (metre)* m* moment of Capacitance c farad F Capacity V litres 1 Coefficient of No unit friction Zioefficient of α per degree rc linear expansion Celsius Conductance G seimens s Cubical expan y per degree rc sion, coeffi Celsius cient of Current I ampere A Density ρ kilogram per kg/m3 cubic metre Density, relative d no unit Dryness fraction X no unit Efficiency η no unit Elasticity, Ε Pascal Pa modulus of (1 Pa = l N/m^) Electric field Ε volts per metre V/m strength Quantity Quantity symbol Unit Unit symb Electric flux D coulomb per C/m2 density square metre Energy W joules J Energy, internal U, Ε joules J Energy, specific u, e kilojoules per kj/kg internal kilogram Enthalpy Η joules J Enthalpy, specific h kilojoules per kJ/kg kilogram Entropy S kilojoules per kJ/K kelvin Expansion: y per degree /°C coefficient of Celsius cubical coefficient α per degree /°C of linear Celsius coefficient of β per degree /°C superficial Celsius Field strength: Ε vvoollttss ppeerr mmeettrree V/m electric magnetic Η ampere per metre A/m Flux: D coulomb per C/m2 electric square metre magnetic Β tesla Τ Flux: electric coulomb C magnetic Φ weber Wb Force F newtons Ν Frequency f hertz Hz Heat capacity. c kilojoules per kj/(kg K) specific kilogram kelvin Impedance Ζ ohm Ω Inductance: self L henry Η mutual Μ henry Η Internal energy υ, Ε joules J specific U, e kilojoules per kJ/kg kilogram Inertia, moment IJ kilogram metre kkggmm22 of squared Length 1 metre m
The list of books you might like
