The Flying Circus of Physics

348 Pages·2006·33.7 MB·English

by  Jearl Walker

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Library of Congress Cataloging in Publication Data:
Walker, Jearl
The flying circus of physics / Jearl Walker.--2nd ed.
p.cm.
Includes index.
ISBN-13: 978-0-471-76273-7 (pbk.: acid-free paper)
ISBN-lO: 0-471-76273-3 (pbk.: acid-free paper)
1. Physics--Problems, exercises, etc. I. Title.
QC32.W2 2007
530--dc22
2006008029
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
This book is dedicated to my wife
Mary Golrick
who sat with me for the 13 years I wrote "The Amateur Scientist" for Scientific
American, the 16 years (and still counting) I spent writing Fundamentals of
Physics, and the 200 years (seemingly) I spent on developing and writing this
edition of The Flying Circus of Physics. Without her encouragement, support, love,
and tolerance, I would have ended up staring at the wall instead of a word
processing screen.

p • R • E • F • A • c • E
The Flying Circus of Physics began one dark and dreary Web site for The Flying Circus of Physics
night in 1968 while I was a graduate student at the
The web site associated with this book can be found at
University of Maryland. Well, actually, to most graduate
www.flyingdrwsofphysics.com and contains:
students nearly all nights are dark and dreary, but I mean
• Over 10 000 citations to journals and books of science,
that particular night was really dark and dreary. I was a
engineering, math, medicine, and law. The citations are
full-time teaching assistant, and earlier in the day I had
grouped according to the items in the book and marked as
given a quiz to Sharon, one of my students. She did badly
to difficulty.
and at the end turned to me with the challenge, "What has
anything of this to do with my life?" • Bonus items.
I jumped to respond, "Sharon, this is physics! This has • Corrections, updates, and additional comments.
everything to do with your life!"
• An extended index.
As she turned more to face me, with eyes and voice both
tightened, she said in measured pace, "Give me some
Origin of the Flying Circus name
examples."
I thought and thought but could not come up with a sin I named my original collection of problems after the very
gle one. I had spent at least six years studying physics and I early airshows in which daredevil pilots performed hair
could not come up with even a single example. raising stunts. I thought such an airshow was generically
That night I realized that the trouble with Sharon was known as a "flying circus" and hoped that the image of dare
actually the trouble with me: This thing called physics was devil pilots would entice someone to read my words.
something people did in a physics building, not something I've since learned that a flying circus was originally a cir
that was connected with the real world of Sharon (or me). So, cus that moved about on a train and then later the name
I decided to collect some real-world examples and, to catch given to German aircraft that were moved in that way. The
her attention, I called the collection The Flying Circus of term came to be associated with the famous German pilot
Physics. Gradually I added to the collection. Red Baron, who in World War I painted his airplane blood
Soon other people wanted copies of the Flying Circus red to scare the pilots he fought in the air.
material, first students in Sharon's class, then my fellow grad The comedy troupe known as Monty Python'S Flying
uate students, and then some of the faculty members. After Circus first appeared in England about a year after I had
the material was printed as a "technical report" by the Physics begun using the Flying Circus name. The name must have
Department at Maryland, I landed a book contract with John just been in the air on both sides of the Atlantic Ocean that
Wiley & Sons. year. (The "dead parrot routine" is, however, entirely Monty
The book was published in 1975, a few years after I Python's.)
became a physics professor at Cleveland State University; it
was revised in 1977. Since then it has been translated into 11
Bibliography
languages for publication around the world. This is the sec
ond edition of the book, which is completely rewritten and All citations are listed in the Flying Circus ofP hysics web site,
redesigned. grouped according to the items here in the book, and marked
When I began writing Flying Circus material, I searched as to mathematical difficulty. The site contains over 10000
through only a few dozen research journals, page by page, citations.
and discovered few relevant papers. Indeed, my metaphor for
the project was that I was digging for gold in an almost bar
Sending stuff to me
ren mountainside-the gold nuggets were few and hard to
find. I would very much enjoy receiving corrections, comments,
The world has changed: Now, many hundreds of research new ideas, and citations. If the latter, I would appreciate if
papers with potential Flying Circus material are published you would send the full citation without abbreviations and
every year and, in terms of my metaphor, I find huge gold with the full page numbers, but if that is not possible, even a
veins. And now I don't dig through just a few dozen journals; scrap will interest me. If you can send me a photocopy of a
I look through about 400 journals directly and use search paper or a web site address, that would be great.
engines to sort through hundreds more. On many days my I generally do not list web sites in the citations because I
fmgers just fly over my computer keyboard. I wish Sharon cannot frequently check whether the web sites remain active.
could look over my shoulder at all the really curious things I I teach full time, work on this book full time, and work on
find. With this book you get that chance: Come look over my the textbook Fundamentals of Physics twice full time. That is
shoulder and you'll see that physics "has everything to do a lot of full times, and yet I am only finite. So, please under
with your life." stand why I cannot answer every letter or note.
viii • PREFACE www.flyingcircusofphysics.com
Cleveland State University the book work to hire me as an Assistant Professor at
Cleveland State University), David Halliday and Robert
If you want to attend a solid, middle-size university, come to
Resnick (who allowed me to take over their textbook
Cleveland State University (www.csuohio.edu) in Cleveland,
Fundamentals of Physics in 1990), Ed Millman (who tutored
Ohio. I have been teaching here for over 30 years and have no
me on how to write textbooks), Mary Jane Saunders (the
intention of stopping (although I hear that Nature will even
Dean of the College of Science at CSU, who set up such a
tually slow me down). I'm the fellow in the small office, sur
positive atmosphere that this edition of The Flying Circus of
rounded by research papers, with my fingers flying over a
Physics was possible and who critically reviewed many of the
keyboard desperately trying to meet yet another publication
manuscript pages), Stuart Johnson (the physics editor at
deadline.
John Wiley & Sons who guided me through this book and
multiple editions of Fundamentals of Physics), Carol Seitzer
Textbooks (who read through the manuscripts for this book, making
many solid changes), Madelyn Lesure (the designer of this
The material in this book assumes that you took elementary
book), Elizabeth Swain (the production editor at John Wiley
physics or physical science in grade school. If you want a good
& Sons who managed the production of this book), Chris
textbook to go with this book, here are some suggestions:
Walker, Heather Walker, and Claire Walker (my grown chil
• How Things Work: The Physics of Everyday Life, Louis A.
dren who tolerated my obsession with writing and teaching
Bloomfield (John Wiley & Sons), non-mathematical
their entire lives), Patrick Walker (my growing child-not
introduction to physics
only did he tolerate the many years I spent working in the
• Physics, John D. Cut nell and Kenneth W. Johnson (John basement, but he also taught me how to climb the overhang
Wiley & Sons), algebra-based introduction to physics at the rock-climbing gym), and (most of all) Mary Golrick
• Fundamentals of Physics, David Halliday, Robert (my wife, who contributed many ideas to this edition and
Resnick, and Jearl Walker (John Wiley & Sons), calculus who kept me going whenever I exclaimed, "All hope is lost!").
based introduction to physics
Physics for. ..
Acknowledgments
• a first date: 1.57, 1.75, 1.122, 1.124,2.51,2.90,4.78,
I have many people to thank because they encouraged me at 5.17,5.19,6.98,6.122,7.15,7.16,7.50
times when I thought, "All hope is lost!" Well, ok, that is part
• a pub: 1.110, 1.122, 1.149,2.10,2.24,2.25,2.51,
of the reason. The rest is that many people tolerated me when
2.76-2.78,2.87-2.91,2.96,2.108,2.120,3.27,3.40,4.24,
I became completely obsessed and thought, "I need to work
4.42, 4.60,4.78,6.98,6.113, 6.130, 6.136, 6.138
as if there is no tomorrow!"
• an airplane trip: 1.17,1.18,4.53,4.69, 5.34,5.35,
6.10,6.34, 6.35,6.37,6.44,6.63, 6.91,6.100,6.105,6.129
Jearl and Martha Walker (my parents, who, when I was a
teenager, surely spent many sleepless nights worrying • a bathroom and toilet: 1.93,1.193,2.21,2.23,2.41,
whether I would end up successful or incarcerated), Bob 2.60,2.150,3.67,4.65,4.66,6.88,6.99,6.110
Phillips (my high school math and physics teacher who • a garden: 1.132,2.11, 2.80, 2.93, 2.94,2.99,3.25,4.29,
opened new worlds for me), Phil DiLavore (who got me 4.57,4.84,5.32,6.84,6.92,6.115,6.118,6.120,6.121,6.126,7.38
started in teaching), Joe Reddish (who was instrumental in
getting the original notes of The Flying Circus of Physics pub
I invite you to create other groupings of problems for certain
lished as a technical report by the University of Maryland
occasions and locations.
Physics Department), Phil Morrison (who was the first to a
encourage me to publish the technical report as a book and
who then wrote a nice review about the book in Scientific
~
learl Walker
American, which probably got me the 13-year job of writing
the magazine's "Amateur Scientist" section), Dennis Flanagan Department of Physics
(the editor at Scientific American, who hired me and then College of Science
guided me for years), Donald Deneck (the physics editor at Cleveland State University
John Wiley & Sons in the early 1970s, who offered me the 2121 Euclid Avenue
first book contract for The Flying Circus of Physics), Karl Cleveland, Ohio USA 44115
Casper and Bernard Hammermesh (who thought enough of Fax: USA 216.687.2424
• •
C • 0 • • T • E • • T • S
Brief Contents 4 Striking at the Heat in the Night
Preface VII (THERMAL PROCESSES) 178
5 Ducking First a Roar and Then a Flash
I Slipping Between Falling Drops
(MOTION) I (ELECTRICITY AND MAGNETISM) 21 8
2 Racing on the Ceiling, Swimming Through Syrup 6 Splashing Colors Everywhere, like a Rainbow
(FLUIDS) 83 (OPTICS) 242
7 Armadillos Dancing Against a Swollen Moon
3 Hiding under the Covers, listening for the
Monsters (VISION) 305
(SOUND) 147 Index 325
Contents
Preface VII 1.30 Bolas 14
1.31 Siege machine 14
CHAPTER I 1.32 Human cannonball 15
1.33 Basketball shots 15
Slipping Between Falling Drops
1.34 SHORT STORY: Records in free throws 16
(MOTION) I
1.35 Hang time in basketball and ballet 16
1.1 Run or walk in the rain? I 1.36 Golfing 17
1.2 Traffic platoons and gridlock 1.37 SHORT STORY: Curtain of death of a meteor
1.3 Shock waves on the freeway strike 17
I A Minimum trailing distance for a car 2 1.38 The high jump and the long jump 17
1.5 Running a yellow light 2 1.39 Jumping beans 19
1.6 Spinout during hard braking 2 1.40 Somersault of a click beede, attack of a mantis
1.7 To slide or not to slide 3 shrimp 19
1.8 Skidding to a stop 4 I A I SHORT STORY: Some record lifts 20
1.9 SHORT STORY: Some records for skid marks 5 1042 Chain collisions 20
1.10 Woodpeckers, bighorn sheep, 1,43 Dropping a stack of balls 21
and concussion 5 1044 SHORT STORY: A crashing demonstration 22
1.1 I SHORT STORY: The game of gs 5 1045 Karate 22
1.12 Head-on car collision 6 1.46 Boxing 23
1.13 SHORT STORY: Playing with locomotives 6 1047 Skywalk collapse 24
1.14 Rear-end collision and whiplash injury 6 1.48 World Trade Center collapse 24
1.15 Race-car turns 6 1.49 Falls from record heights 24
I. 16 Sprint tracks 7 1.50 A daring parachuting rescue 25
I. 17 Takeoff illusion 7 1.51 Cats In long falls 25
1.18 SHORT STORY: Air Canada Flight 143 7 1.52 Land diving and bungee jumping 26
1.19 Fear and trembling at the amusement park 8 1.53 Trapped in a falling elevator cab 26
1.20 SHORT STORY: Circus loop-the-Ioop acts 9 1.54 SHORT STORY: Bomber crashes into Empire State
1.21 Catching a fly ball 10 Building 26
1.22 SHORT STORY: High ball 10 1.55 Falls in fighting, landing during parachuting 27
1.23 Hitting a baseball 10 1.56 Beds of nails 27
1.24 Legal passes in rugby 12 1.57 Hanging spoons 28
1.25 Juggling 12 1.58 Trails of migrating rocks 28
1.26 Pole vaulting 12 1.59 Hitches 28
1.27 Launch of an adad and a toad tongue 12 1.60 Rock climbing 29
1.28 Slings 13 1.61 Rock climbing by bighorn sheep 30
1.29 Tomahawks 14 1.62 Pulling statues across Easter Island 30
x • CONTENTS www.flyingcircusofphysics.com
.63 Erecting Stonehenge 30 14 Incense swing 56
.64 lifting the blocks for the Egyptian pyramids 31 15 The pendulum in the pit 57
.65 A Slinky 32 16 Inverted pendulums, unicycle riders 57
.66 Leaning tower of blocks 32 17 Carrying loads on the head 57
.67 Leaning tower of Pisa 33 18 Carrying loads with oscillating poles 58
.68 Falling dominoes 34 19 Coupled pendulums 58
.69 Falling chimneys, pencils, and trees 34 20 Spring pendulum 59
.70 Breaking pencil points 35 21 The bell that would not ring 60
.71 Failure of a bridge section 35 22 Spaghetti effect 60
.72 Jackknifing of a train 36 23 The spider and the fly 60
.73 Bowling strikes 36 24 Footbridge and dance floor oscillations 61
.74 Shots in pool and billiards 37 25 Precariously balanced structures and rocks 62
.75 Miniature golf 38 26 Sinking of the nuclear submarine Kursk 62
.76 Super Ball tricks 38 27 Detection by sand scorpion 63
.77 Racquetball shots 39 28 Snow waves 63
.78 SHORT STORY: A controversial goal 40 29 Football-stadium wave 63
.79 Tennis 40 30 Body armor 64
.80 Bicycles and motorcycles 41 31 Archer's paradox 64
.81 Motorcycle long jumps 41 32 Oscillating plants 64
.82 Skateboards 42 33 Oscillating tall buildings 65
.83 Pitching horseshoes 42 34 Diving from a springboard 65
.84 Spinning hula hoops and lassos 42 35 Fly casting 65
.85 Yo-yo 43 36 The Falkland Islands battle, Big Bertha 66
.86 Unwinding a yo-yo 44 37 jack and the beanstalk to space 66
.87 Driving through the sound barrier 44 38 Spring fever and the standing of eggs 67
.88 SHORT STORY: Spin test explosion 45 39 Moon madness 67
.89 Kayak roll 45 .140 Gravity hill 68
.90 Curling 45 .141 Falling through the center of Earth 68
.91 Tightrope walk 46 .142 Stretching of plastic shopping bags 69
.92 Bull riding 46 .143 Giant's Causeway and starch columns 69
.93 Tearing toilet paper 46 .144 Broken fingernails 69
.94 Skipping stones and bombs 47 .145 Crumpling paper into a ball 69
.95 Spinning ice-skater 47 .146 Playful to tragiC examples of explosive expansion
.96 Spinning a book 48 70
.97 Falling cat, astronaut antics, and fancy diving 48 .147 Why a hanging picture becomes crooked 70
.98 Quadruple somersault 49 .148 A two-spring surprise 70
.99 Tumbling toast 49 .149 Stability of a pop can 71
.100 Ballet 50 .150 Wilberforce pendulum 71
.101 Skiing 50 .15 I Drag racing starts 71
.102 Abandoned on the ice 51 .152 Turn or stop 72
.103 SHORT STORY: Rotation sequence matters 52 .153 Slipping past a bus 72
.104 Personalities oftops 52 .154 Compression region in sticky tape 72
.105 SHORT STORY: A headstrong suitcase 53 .155 Bobsled in a curve 72
.106 Tippy tops 53 .156 Too quick to slide 73
.107 Spinning eggs 53 .157 The home of the little Prince 73
.108 Diabolos 53 .158 Parachuting with a pumpkin 73
. I 09 Rattlebacks 54 .159 Pulling in a feisty fish 73
.1 10 Wobbling coins and bottles 54 .160 Fiddlesticks 74
.111 Judo, aikido, and Olympic wrestling 55 .161 Rotor on a notched stick 74
.1 12 Bullet spin and long passes 55 .162 Shot put and hammer throw 74
.1 13 Pumping playground swings 56 .163 Jumps during downhill ski race 75
www.flyingcircusofphysics.com CONTENTS • xi
1.164 Pulling a tablecloth beneath dishes 75 2.15 Golf-ball aerodynamics 88
1.165 SHORT STORY: Pulling with teeth 75 2.16 Baseball aerodynamics 89
1.166 Jerking chair 75 2.17 Cricket aerodynamics 89
1.167 Lifting a person with fingers 76 2.18 Birds flying in V formation 90
1.168 Rockets, and a problem with an iceboat 76 2.19 Speed swimming in syrup 90
1.169 SHORT STORY: Earth to Venus 76 2.20 Contrails 90
1.170 A choice of hammers 77 2.21 Inward flutter of a shower curtain 91
1.171 Pressure regulator 77 2.22 Prairie dog and giant ant nests 91
1.172 Sliding a stick across fingers 77 2.23 Bathtub vortex 92
1.173 SHORT STORY: Giant tug-of-war 77 2.24 Vortex in a cup of coffee 92
1.174 Shooting along a slope 77 2.25 Gathering of tea leaves, spinning of olives 91
1.175 Starting a car on a slippery road 78 2.26 Meandering rivers 93
1.176 Balancing a tire 78 2.27 Bird spinning in water 94
1.177 Carnival bottle swing 78 2.28 Water climbing a spinning egg 94
1.178 Hanging goblet. ready to crash 78 2.29 Circular water-flow pattern in a sink 94
1.179 Breaking a drill bit 79 2.30 Water level in canals 94
I.ISO Swinging watches 79 2.31 Solitary waves 95
1.181 SHORT STORY: Flattening the Golden Gate 2.32 Tidal bores 95
2.33 Tides 95
Bridge 79
1.182 Hunting by railway vehicles 79 2.34 Tides in the Bay of Fundy 96
.183 Oscillating car antenna 79 2.35 Dead water 96
.184 A ship's anti roll tank 80 2.36 Tornadoes 96
.185 Road corrugation 80 2.37 SHORT STORY: Looking up into a tornado 97
.186 Seeing only one side of the Moon 80 2.38 Waterspouts and funnel clouds 97
.187 Intelligence satellites 80 2.39 Dust devils. fog devils, and steam devils 97
2."10 Ring vortexes 98
.188 Air drag speeds up satellite 81
.189 Moon trip figure eight 81 2."1 I Siphons and toilets 99
2."12 Lizards walking on water 99
.190 Earth and Sun pull on Moon 81
2."13 lead bar floating in a boat 99
.191 Gravitational slingshot effect 81
2,44 Floating bars and open containers 100
.192 Making a map of India 81
2."15 Hole in a dam. ship in dry dock 100
.193 Shaving with twin blades 81
2."16 g-lOC in pilots 100
.194 The handedness of river erosion 82
2.47 Blood circulation in snakes, giraffes, and tall
CHAPTER 2 dinosaurs 100
Racing on the Ceiling, Swimming Through Syrup 2."18 Did the sauropods swim? 101
2."19 Gastroliths in dinosaurs and crocodiles 101
(FLUIDS) 83
2.50 Coanda effect 101
2.1 Race cars on the ceiling 83 2.51 Teapot effect I 02
2.2 Drafting 83 2.52 Ascents after deep diving 103
2.3 Aerodynamics of passing trains 84 2.53 Snorkeling by people and elephants 103
2."1 Collapse of the old Tacoma Narrows Bridge 84 2.54 Deep diving submarine escape 103
2.5 Aerodynamics of buildings 84 2.55 lake Nyos disaster 104
2.6 Kites 85 2.56 SHORT STORY: House-hopping. and riding the
2.7 Ski jumping 85 skies in a lawn chair 105
2.8 Speed of a downhill skier 86 2.57 Flow of medieval cathedral window glass 105
2.9 Boomerangs 86 2.58 Strange viscous fluids 105
2.10 Throwing cards 86 2.59 Soup reversal 106
2.1 I Seeds that spin 87 2.60 Bouncing liquid stream 106
2.12 Flying snakes 87 2.61 Rod-climbing fluids 107
2.13 Air drag on tennis balls 88 2.62 Liquid rope coils 107
2.14 Veering a football around a defensive wall 88 2.63 Water waves 107