The New Way Things Work

402 Pages·1998·96.149 MB·English

by  David Macaulay

THE
NEW
WAY
THINGS
WORK
--
----
THE
WAY
) THINGS
W O R K
DAVID MACAULAY
WITH
NEIL ARDLEY
DORLING KINDERSLEY
London • New York • Moscow • Sydney
A DORLINC. KINDER!:>LL Y BOOK
Project Editor DaVld Burme
Designer Peter LuH
Revised Edition
Senior Editor Sue Leonard
An Editor Cath) Chesson
Produc1ion Kate Oliver
First published m Great Bntam m 1988
by Dorlmg Kmdersle} Ltm!led. London
9 Hcnricua Street, London WC21.: 8PS
Rcpnnted 1989, 1990 (twtce), 1991, 1992, 1994, 1995, 1996. 1997
ReVIsed Edlllon 1998
Compilation copyright© 1988. 1998 Dorhng Kindersh::y Limited, London
lllust ration copynght © 1988, l 998 Davtd Mucaulay
Text copyright © 1988. 1998 Davtd MacHulay, Neil Ardle}'
Originally pubhshed as ntr Way Th111gs Worl1
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All nghts reserved. No pan of tlus pubbcuuon may be reproduced, stored m a retneval system,
or transmmed in any fom1 or by any means, electronic, mechanical, photocopying. recording
or otherwise, without the pnor wrmcn pcrmtSston of the copynght owner
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ISBN 0 751156411
Colour reproduction by Colour..can, Smgaporc
Pnnted m Spam by Anes Graftc:~s Toledo. SA
D.L. TO: 1033-1998
CONTENTS
PART l
THE
MECHANICS OF
MOVEMENT 6
PART2
HARNESSING THE
ELEMENTS 90
PART3
WORKING WITH
174
WAVES
PART4
&
ELECTRICITY
254
AUTOMATION
PARTS
THE DIGITAL
DOMAIN 310
- -
- - - -
EUREKA!
THE INVENTION OF
3 74
MACHINES
TECHNICAL TERMS 390
INDEX 396
WORK
EARLY~
- - -ON- - -
THE4RQTATJQN
OF4THJE~EARTH
PART l
THE MECHANICS
OF MOVEMENT
INTRODUCTION 8
THE INCLINED PLANE 10
LEVERS 18
THE WHEEL & AxLE 30
GEARS & BELTS 36
CAMS & CRANKS 48
PULLEYS 54
SCREWS 62
ROTATING WHEELS 70
SPRINGS 78
FRICTION 82
THE MECHANlCS OF MOVEMENT
INTRODUCTION
To MY MACIIINE, work is a mauer of princtple, because everything a machine does is in
accordance wtlh a set of principles or sctenufic laws. To see the way a machine works,
you can take the covers off and look inside. But to understand what goes on, you need to
get to know the pnnctples that govern Its actions. The machmes m thts and the following
parts of The New Way Things Work are therefore grouped by their principles rather than by
their uses. This produces some interesting neighbours the plough rubs shoulders whh the
zipper, for example, and Lhe hydroelectric power station wtth the dentists drill. They may
look different, be vastly dillerem in scale, and have different purposes,
but when seen in terms of principles, they work in the same way
MACHINERY IN MOTION
Mechanical machines work with parts that move. These pans include levers, gears, belts,
wheels, cams, cranks, and springs, and they are often interconnected in complex linkages,
some large enough to move mountains and others almost mvlSible. Their movement can be
so fast that It d1sappears in a blur of spinnmg axles and whtrlmg gears, or tt can be so slow
that nothing seems to be moving at all. But whatever the1r nature, all machines that use
mecharucal pans are built with the same smgle atm. to ensure that exactly Lhe nght amount
of force produces just the right amount of movement prectsely where it lS needed.
MOVEMENT AND FORCE
Many mechamcal machmes exist to conven one form of movement mto another. This
movement may be in a straight line (in which case It ts often backward~and~forward, as in
the shuttlmg of a ptston-rod) or It may be m a ctrcle. Many machines convert linear
movement into circular or rotary movement and vice-versa, often because the power source
dnvmg the machine moves in one way and the machme in another. But whether direction is
altered or not, the mechanical parts move to change the force applied into one- either
larger or smaller- that is appropriate for the task to be tackled. Mechanical machines all
deal Wllh forces. In one way Lhey are just like people when it comes to getting them on the
move: it always takes some effort. Movement does not simply occur of its own accord, even
when you drop something. It needs a driving force - the push of a motor, the pull of muscle
or gravity, for example. ln a machine, this driving force must then be conveyed to the right
place in the right amount.When you squeeze and twist the handles of a can opener, the
blade cuts easily through the lid of the can. This device makes light work of something that
would otherwise be impossible. It does th1s not by g1vmg you strength that you do not have,
but by convening the force that your wrist produces into the most useful form for the job-
in this case, by increasing it - and applymg 1t where n ts needed.
INTRODUCTION
HOLDlNG MATTER TOGETHER
Every object on Earth is held together and in place by three bas1c kinds of force;
virtually all machmes make t15e of only two of them. The first kind of force 15 graVIty, whtch
pulls any two pieces of maner together. Gravity may seem to be a very strong force, but in
fact it is by far the weakest of the three. Its effects are noticeable only because it depends on
the masses of the two pieces of matter involved, and because one of these pieces of mauer
the whole Earth - is enormous. The second force is the electrical force that exists between
atoms. This is responstble for electricity, a subject explored m Part 4 of the book. Electrical
force binds the atoms that make up all matcnals, and it holds them wgether with
tremendous strength. Movement in machines is transmitted-unless the parts break-only
because the atoms and molecules (groups of atoms) in these pans are held together by
electrical force. So all mechanical machines use Lhis force indirectly. In additton, some
machmes, such as springs and friction devices, use it directly, both to produce movemem
and to prcvem it. The third and strongest force is the nuclear force that binds particles in
the nuclei of atoms. This force is released only by machines that produce nuclear power.
THE CONSERVATION OF ENERGY
Underlying the actions of all machines 15 one principle which encompasses all the olhers -
the conservation of energy. This is not about savtng energy. but aboUL what happens to
energy when it is used. It holds that you can only get as much energy out of a machine as
you put into it in the ftrst place - no more and no less. As a motor or muscles move to
supply force to a machine, they give it energy; more force or more movement provides more
energy. Movement is a form of energy called kmeuc energy. ll is produced by convemng
other fom15 of energy. such as the potential energ) stored m a spring, the heat in a petrol
engme, the electric energy in an electric motor, or the chem1cal energy in muscles. When a
machine transmus force and applies it, it can only expend the same amount of energy as
that put into It to get things moving. Lf the force the machine apphes IS to be greater, then
the movement produced must be correspondingly smaller, and vice-versa. Overall. the total
energy always rema1ns the same. The principle of conservation of energy governs all actions.
Springs may store energy, and friction will convert energy to heat, but when everything is
taken into account, no energy is created and none destroyed. lf the principle of conservation
of energy were to vanish, then nothing would work. If energy were destroyed as machines
worked, then, no matter how powerful they might be, they would all slow down and stop.
And if the workings of machines created energy, then all machines would get faster and
faster in an energy build-up of titanic proportions. Either way, the world would end - wlth a
whimper m one case and a bang in the other. But the principle of conservation of energy
..Iii:.
holds good and all machines obey. Or nearly all. Nuclear machines are an exception
..
- but that is a swry for the second pan of this book. ~--
.-.
L---------------------------- - - r~
~
THE MECHANICS OF MOVEMENT
THE INCLINED PLANE
ON CAPWRING A MAMMOTH
I n the spring of that year, I was invited to the land of the
much sought-after woolly mammoth, a land dotted by
the now familiar high wooden towm of the mammoth
captors. In ancient times the mammoth had been hunted
simply for its meat. But its subsequent usefulness in
industry and growing popularity as a pet had brought
about the development of a more sophisticated and less
tenninal means of apprehension.
Each unsuspecting beast was lured to the base of a tower
from which a boulder of reasonable dimensions was then
dropped from a humanitarian height onto its thick skull.
Once ~nedra mammoth could easily be lead to the
p,addock whlre an ice pack and fresh swamp grass would
quickly<(Vercome hurt feelings and innate distrust
lliE PRINCIPLE OF 1l-IE INCLINED PLANE
distance is greatest The work you do is the same in either
The laws of physics decree that raising an object, such as a case, and equals the effort (the force you exert) multiplied
mammoth-stunning boulder, to a particular height requires by the distance over which you maintain the effort.
a certain amount of work. Those same laws also decree that So what you gain in effort, you pay in distance. This is a
no way can ever be found to reduce that amount The ramp basic rule that is obeyed by many mechanical devices, and it
makes life easier not by altering the amount of work that is is tl1e reason why the ramp works: it reduces the effort needed
needed, but by altering the way in which the work is done. to raise an object by increasing the distance that it moves.
Work has two aspects to it: the effort that you put in, and The ramp is an example of an inclined plane. The
the distance over which you maintain the effort. lf the principle behind the inclined plane was made use of in
effort increases, the distance must decrease, and vice versa. ancient times. Ramps enabled the Egyptians to build their
This is easiest m understand by looking at two extremes. pyramids and temples. Since then, the inclined plane has
Climbing a hill by the steepest route requires the most effort, been put to work in a whole host of devices from locks and
but the distance that you have to cover is shortest. Climbing cutters to ploughs and zippers, as well as in all the many
up the gentlest slope requires the least effort, but the machines that make use of the screw.
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