Motion Mountain - The Adventure of Physics, Vol 1 of 6 - Fall, Flow and Heat

466 Pages·2011·52.14 MB·English

by  Christoph Schiller

Christoph Schiller
MOTION MOUNTAIN
the adventure of physics – vol.i
fall, flow and heat
www.motionmountain.net

ChristophSchiller
Motion Mountain
The Adventure of Physics
Volume I
Fall, Flow and Heat
Edition24.24,available asfreepdfat
www.motionmountain.net
Editiovicesimaquarta.
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quartoannoOlympiadisvicesimaenonae.
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Twenty-fourthedition.
Copyright©2011byChristophSchiller,
thefourthyearofthe29thOlympiad.
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ToBritta,EstherandJustusAaron
τῷἐμοὶδαὶμονι
DieMenschenstärken,dieSachenklären.
PREFACE
“Primummovere,deindedocere.* ”
Antiquity
This book is written for anybody who is curious about nature and motion. Curiosity
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about how people, animals, things, images and space move leads to many adventures. tio
n
Thisvolumepresentsthebestoftheminthedomainofeverydaylife. Mo
u
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Carefully observing everyday motion allows us to deduce six essential statements: tain
everyday motion is continuous, conserved, relative, reversible, mirror-invariant – and –Th
e
lazy.Yes,natureisindeedlazy:ineverymotion,itminimizeschange.Thistextexplores A
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howthesesixresultsarededucedandhowtheyfitwithallthoseobservationsthatseem ntu
tocontradictthem. reo
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formIntthheemstraujocrtupraerotfomftohdeesrtnarptihnygsipcos,inshtoatwtnheinboFtitgoumre.1Th,theeprreessuenlttsvoonluemveeryisdtahyemfiorstitoonf hysics
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asix-volumeoverviewofphysics.ItresultedfromathreefoldaimIhavepursuedsince f
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199I0n:toordperresteonbtemsiomtipolne,itnheatweaxytftohcautsiesssiomnpcloen,uceppttos,dwahteilaenkdeecpaipntgivmatianthge.maticstothe availab
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necessary minimum. Understanding the concepts of physics is given precedence over free
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usingformulaeincalculations.Thewholetextiswithinthereachofanundergraduate. fch
Inordertobeuptodate,thetextisenrichedbythemanygems–boththeoreticaland arg
e
empirical–thatarescatteredthroughoutthescientificliterature. atw
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Inordertobecaptivating,thetexttriestostartlethereaderasmuchaspossible.Read- w.m
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ing a book on general physics should be like going to a magic show. We watch, we are tio
n
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astonished, we do not believe our eyes, we think, and finally we understand the trick. o
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Whenwelookatnature,weoftenhavethesameexperience.Indeed,everypagepresents tain
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atleastonesurpriseorprovocationforthereadertothinkabout.Numerousinteresting et
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challengesareproposed. o
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Themottoofthetext,dieMenschenstärken,dieSachenklären,afamousstatementby yrig
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HartmutvonHentigonpedagogy,translatesas:‘Tofortifypeople,toclarifythings.’Clar- ©
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ifyingthingsrequirescourage,aschanginghabitsofthoughtproducesfear,oftenhidden risto
p
byanger.Butbyovercomingourfearswegrowinstrength.Andweexperienceintense h
S
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and beautifulemotions.Allgreatadventuresin life allow this, and exploringmotion is iller
oneofthem.Enjoyit. No
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Munich,24June2011. 19
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*‘Firstmove,thenteach.’Inmodernlanguages,thementionedtypeofmoving(theheart)iscalledmotivat- ne
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ing;bothtermsgobacktothesameLatinroot. 01
1
8 preface
PHYSICS: Unified description of motion Why does motion
Describing motion with action. Adventures: understanding occur? What are
motion, intense joy with space, time and
thinking, catching a quantum particles?
glimpse of bliss,
calculating
masses and
couplings.
Quantum
General relativity theory with gravity Quantum field theory
Adventures: the Adventures: bouncing Adventures: building
night sky, measu- neutrons, under- accelerators, under-
ring curved space, standing tree standing quarks, stars,
exploring black growth. bombs and the basis of
holes and the life, matter, radiation. Mo
universe, space How do small tionM
and time. things move? ou
n
What are things? tain
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How do The
Classical gravity everyday, Special relativity Quantum theory Adve
Adventures: fast and large Adventures: light, Adventures: death, ntu
climbing, skiing, things move? magnetism, length sexuality, biology, reo
f
space travel, contraction, time enjoying art and P
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the wonders of dilation and colours, all high-tech ysics
astronomy and E0 = mc2. business, medicine, pd
geology. chemistry, evolution. ffi
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G c h, e, k availab
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Galilean physics, heat and electricity freeo
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Adventures: sport, music, sailing, cooking, ch
describing beauty and understanding its origin, arge
using electricity and computers, atw
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understanding the brain and people. w
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FIGURE 1 Acompletemapofphysics:theconnectionsaredefinedbythespeedoflightc,the tion
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gravitationalconstantG,thePlanckconstanth,theBoltzmannconstantkandtheelementarychargee. ou
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Inmyexperienceasateacher,therewasonelearningmethodthatneverfailedtotrans- Ch
form unsuccessful pupilsintosuccessful ones: if you readabook for study, summarize ristop
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every section you read, in your own words, aloud. If you are unable to do so, read the Sch
section again. Repeat this until you can clearly summarize what you read in your own iller
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words,aloud.Youcandothisaloneinaroom,orwithfriends,orwhilewalking.Ifyou vem
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icantly. In addition, you will enjoy learning from good texts much more and hate bad 97
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textsmuchless.Mastersofthemethodcan use itevenwhilelisteningtoalecture,ina Jun
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lowvoice,thusavoidingtoevertakenotes. 01
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preface 9
Using this book
Textingreen,asfoundinmanymarginalnotes,marksalinkthatcanbeclickedinapdf
reader. Such green links are either bibliographic references, footnotes, cross references
tootherpages,challengesolutions,orpointerstowebsites.
Solutionsandhintsforchallengesaregivenintheappendix.Challengesareclassified
as research level (r), difficult (d), standard student level (s) and easy (e). Challenges of
typer,dorsforwhichnosolutionhasyetbeenincludedinthebookaremarked(ny).
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Apapereditionofthisbook,printedondemandanddeliveredbymailtoanyaddress, w
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canbeorderedatstores.lulu.com/motionmountain.Butaboveall,enjoythereading! o
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Contents
14 1 Why should we care about motion?
Doesmotionexist? 15 •Howshouldwetalkaboutmotion? 17 •Whatarethe
typesofmotion? 19 •Perception,permanenceandchange 23 •Doestheworld
needstates? 25 •Galileanphysicsinsixinterestingstatements 27 •Curiosities
andfunchallengesaboutmotion 28 •Summaryonmotion 31
32 2 From motion measurement to continuity
What is velocity? 33 •What is time? 38 •Clocks 41 •Why do clocks go
clockwise? 44 •Doestimeflow? 45 •Whatisspace? 45 •Arespaceand
timeabsoluteorrelative? 48 •Size–whyareaexists,butvolumedoesnot 49 •
Whatisstraight? 54 •AhollowEarth? 55 •Curiositiesandfunchallengesabout
everydayspaceandtime 56 •Summaryabouteverydayspaceandtime 66 M
o
tio
68 3 How to describe motion – kinematics n
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Throwing,jumpingandshooting 70 •Enjoyingvectors 73 •Whatisrest?What u
n
isvelocity? 74 •Acceleration 76 •Objectsandpoint particles 78 •Legs and tain
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wheels 81 •Curiosities and fun challenges about kinematics 83 •Summary of Th
e
kinematics 84 Ad
ve
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86 4 From objects and images to conservation ture
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Motionandcontact 87 •Whatismass? 88 •Momentumandmass 90 •Ismo- fP
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tioneternal?–Conservationofmomentum 95 •Moreconservation–energy 96 ysics
•Thecrossproduct,orvectorproduct 99 •Rotation 101 •Rollingwheels 105 • p
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Howdowewalk? 106 •Curiositiesandfunchallengesaboutconservation 107 fi
le
•Summaryonconservation 113 availab
114 5 From the rotation of the earth to the relativity of motion le
HowdoestheEarthrotate? 121 •DoestheEarthmove? 125 •Isvelocityabsolute? freeo
f
–Thetheoryofeverydayrelativity 130 •Isrotationrelative? 132 •Curiositiesand charg
funchallengesaboutrelativity 132 •Legsorwheels?–Again 137 •Summaryon e
at
Galileanrelativity 139 ww
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141 6 Motion due to gravitation o
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Propertiesofgravitation 145 •Thegravitationalpotential 148 •Theshapeofthe nm
o
u
Earth 150 •Dynamics–howdothingsmoveinvariousdimensions? 152 •Gravita- n
tioninthesky 152 •TheMoon 155 •Orbits–andconicsections 157 •Tides 160 • tain.n
et
Canlightfall? 164 •Whatismass?–Again 165 •Curiositiesandfunchallenges
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aboutgravitation 166 •Summaryongravitation 181 pyrig
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182 7 Classical mechanics and the predictability of motion t©
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plete states – initial conditions 190 •Do surprises exist? Is the future deter- ch
mined? 191 •Freewill 193 •Summaryonpredictability 194 •Globaldescrip- iller
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tionsofmotion 194 vem
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199 8 Measuring change with action er
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Theprincipleofleastaction 203 •Lagrangiansandmotion 206 •Whyismotion 7–
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sooftenbounded? 208 •CuriositiesandfunchallengesaboutLagrangians 211 • ne
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Summaryonaction 214 01
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