Contents
Preface ix
Part One General Engineering Science 1
1 SI units 3
2 Density 6
3 Scalar and vector quantities 8
4 Atomic structure of matter 10
5 Chemical reactions 15
6 Standard quantity symbols and their units 18
Part Two Mechanical Engineering and Physical Science 21
7 Speed and velocity 23
8 Acceleration 27
9 Force, mass and acceleration 30
10 Centre of gravity and equilibrium 34
11 Forces acting at a point 36
12 Simply supported beams 46
13 Shearing force and bending moments 50
14 Bending stress 54
15 Linear and angular motion 57
16 Friction 63
17 Waves 66
18 Interference and diffraction 70
19 Light rays 75
20 Work, energy and power 81
21 Potential and kinetic energy 84
22 Simple machines 88
23 The effects of forces on materials 96
24 Tensile testing 104
25 Hardness and impact tests 107
26 Measurement of strain 111
27 Linear momentum and impulse 118
28 Torque 121
29 Heat energy 127
30 Thermal expansion 134
31 The measurement of temperature 138
32 Pressure in fluids 149
33 Measurement of pressure 156
34 Ideal gas laws 165
35 Properties of water and steam 170
vi
36 Surface tension and viscosity 176
37 Fluids in motion 182
38 Measurement of fluid flow 187
39 Simple harmonic motion and natural vibrations 198
Part Three Electrical Engineering Science 203
40 An introduction to electric circuits 205
41 Resistance variation 214
42 Chemical effects of electricity 218
43 Series and parallel networks 227
44 Capacitors and capacitance 233
45 Magnetic circuits 244
46 Magnetic materials 255
47 Electromagnetism 261
48 Electromagnetic induction and inductance 271
49 Magnetically coupled circuits 277
50 Electrical measuring instruments and measurements 287
51 Semiconductor diodes 303
52 Transistors 311
53 D.c. circuit theory 327
54 Alternating voltages and currents 341
55 Single-phase series a.c. circuits 349
56 Single-phase parallel a.c. circuits 362
57 D.c. transients 371
58 Operational amplifiers 383
59 Three-phase systems 401
60 Transformers 410
61 D.c. machines 425
62 A.c. motors 446
63 Revision of complex numbers 464
64 Application of complex numbers to series a.c. circuits 471
65 Application of complex numbers to parallel a.c. networks 480
66 Power in a.c. circuits and power factor improvement 485
67 A.c. bridges 492
68 Series resonance and Q-factor 500
69 Parallel resonance and Q-factor 511
70 Introduction to network analysis 519
71 Mesh-current and nodal analysis 525
72 The superposition theorem 531
73 Th
´
evenin’s and Norton’s theorems 537
74 Delta-star and star-delta transformations 547
75 Maximum power transfer theorems and impedance matching 554
76 Complex waveforms 559
77 A numerical method of harmonic analysis 576
78 Dielectrics and dielectric loss 582
79 Field theory 590
80 Attenuators 598
81 Filter networks 610
vii
82 Modulation 616
83 Transmission lines 622
Index 636
Preface
Newnes Engineering Science Pocket Book is intended to provide students,
technicians, scientists and engineers with a readily available reference to the
essential engineering science formulae, definitions and general information
needed during their studies and/or work situation — a handy book to have on
the bookshelf to delve into as the need arises.
The text is divided, for convenience of reference, into three main sections
embracing general engineering science, mechanical engineering and physical
science and electrical engineering science.
The text assumes little previous knowledge and is suitable for a wide
range of courses of study. It will be particularly useful for students studying
for NVQ’s and GNVQ’s, technician certificates and diplomas, for GCSE and
A levels, and for Engineering degrees.
John Bird
University of Portsmouth
Part One General
Engineering
Science
1 SI Units
Units
The system of units used in engineering and science is the Syst
`
eme Interna-
tionale d’Unit
´
es (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.
The basic units in the S.I. system are listed below with their symbols:
Quantity Unit
length metre, m
mass kilogram, kg
time second, s
electric current ampere, A
thermodynamic temperature kelvin, K
luminous intensity candela, cd
amount of substance mole, mol
Prefixes
S.I. units may be made larger or smaller by using prefixes that denote multi-
plication or division by a particular amount. The six most common multiples,
with their meaning, are listed below:
Prefix Name Meaning
T tera multiply by 1 000 000 000 000 (i.e. ð 10
12
)
G giga multiply by 1 000 000 000 (i.e. ð 10
9
)
M mega multiply by 1 000 000 (i.e. ð 10
6
)
k kilo multiply by 1 000 (i.e. ð 10
3
)
m milli divide by 1 000 (i.e. ð 10
3
)
µ
micro divide by 1 000 000 (i.e. ð 10
6
)
n nano divide by 1 000 000 000 (i.e. ð 10
9
)
p pico divide by 1 000 000 000 000 (i.e. ð 10
12
)
Length, area, volume and mass
Length is the distance between two points. The standard unit of length is the
metre, although the centimetre, cm, millimetre, mm and kilometre, km,are
often used.
1cmD 10 mm, 1mD 100 cm D 1 000 mm and 1 km D 1 000 m
4
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
2
1m
2
D 1mð 1mD 100 cm ð 100 cm D 1 0000 cm
2
or 10
4
cm
2
D 1 000 mm ð 1000 mm D 1 000 000 mm
2
or 10
6
mm
2
Conversely, 1 cm
2
D 10
4
m
2
and1mm
2
D 10
6
m
2
Vol ume 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
3
1m
3
D 1mð 1mð 1m
D 100 cm ð 100 cm ð 100 cm D 10
6
cm
3
D 1000 mm ð 1000 mm ð 1000 mm D 10
9
mm
3
Conversely, 1 cm
3
D 10
6
m
3
and1mm
3
D 10
9
m
3
Another unit used to measure volume, particularly with liquids, is the
litre, l,where1lD 1000 cm
3
Mass is the amount of matter in a body and is measured in kilograms, kg.
1kgD 1000 g (or conversely, 1 g D 10
3
kg)
and 1 tonne (t) D 1000 kg
Derived SI Units
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 squared (m/s
2
Charge
The unit of charge is the coulomb (C) where one coulomb is one ampere
second. (1 coulomb D 6.24 ð 10
18
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,
charge, in coulombs
Q
=
It
where I is the current in amperes and t is the time in seconds.
5
Force
The unit of force 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
=
ma
where m is the mass in kilograms and a is the acceleration in metres per
second squared. Gravitational force, or weight, is mg, where g D 9.81 m/s
2
Work
The unitofworkorenergyis 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,
W
=
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.
Power
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, in watts,
P
=
W
t
where W is the work done or energy transferred, in joules, and t is the time,
in seconds. Thus,
energy, in joules,
W
=
Pt
Electrical potential and e.m.f.
The unit of electric potential is the volt (V), where one volt is one joule per
coulomb. One volt is defined as the difference in potential between two points
in a conductor which, when carrying a current of one ampere, dissipates a
power of one watt, i.e.
volts D
watts
amperes
D
joules/second
amperes
D
joules
amperes seconds
D
joules
coulombs
A change in electric potential between two points in an electric circuit is called
a potential difference.Theelectromotive force (e.m.f.) provided by a source
of energy such as a battery or a generator is measured in volts.
2Density
Density is the mass per unit volume of a substance. The symbol used for
density is (Greek letter rho) and its units are kg/m
3
Density D
mass
volume
i.e.
r =
m
V
or
m
= r
V
or
V
=
m
r
where m is the mass in kg, V is the volume in m
3
and is the density in
kg/m
3
Some typical values of densities include:
Aluminium 2700 kg/m
3
Steel 7800 kg/m
3
Cast iron 7000 kg/m
3
Petrol 700 kg/m
3
Cork 250 kg/m
3
Lead 11 400 kg/m
3
Copper 8900 kg/m
3
Water 1000 kg/m
3
For example, the density of 50 cm
3
of copper if its mass is 445 g is
given by:
density D
mass
volume
D
445 ð 10
3
kg
50 ð 10
6
m
3
D
445
50
ð 10
3
D 8
.
9
×
10
3
kg/m
3
or 8900 kg/m
3
Similarly, the volume, in litres, of 20 kg of paraffin oil of density 800 kg/m
3
is given by:
volume D
m
D
20 kg
800 kg/m
3
D
1
40
m
3
D
1
40
ð 10
6
cm
3
D 25 000 cm
3
1 litre D 1000 cm
3
hence 25 000 cm
3
D
25 000
1000
D 25 litres
The relative density of a substance is the ratio of the density of the
substance to the density of water, i.e.
relative density D
density of substance
density of water
Relative density has no units, since it is the ratio of two similar quantities.
Typical values of relative densities can be determined from above (since water
has a density of 1000 kg/m
3
), and include:
Aluminium 2.7 Steel 7.8
Cast iron 7.0 Petrol 0.7
Cork 0.25 Lead 11.4
Copper 8.9
7
The relative density of a liquid may be measured using a hydrometer.
For example, the relative density of a piece of steel of density 7850 kg/m
3
,
given that the density of water is 1000 kg/m
3
, is given by:
relative density D
density of steel
density of water
D
7850
1000
D 7
.
85
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