Download How Things Work, Binder Ready Version: The Physics of Everyday Life PDF

TitleHow Things Work, Binder Ready Version: The Physics of Everyday Life
Author
TagsPhysics
LanguageEnglish
File Size16.4 MB
Total Pages511
Table of Contents
                            Cover
Title Page
Copyright Page
Foreword
Contents
Preface
Acknowledgments
CHAPTER 1 THE LAWS OF MOTION, PART 1
	Active Learning Experiment: Removing a Tablecloth from a Table
	Chapter Itinerary
	1.1 Skating
	1.2 Falling Balls
	1.3 Ramps
	Epilogue for Chapter 1
	Explanation: Removing a Tablecloth from a Table
	Chapter Summary and Important Laws and Equations
CHAPTER 2 THE LAWS OF MOTION, PART 2
	Active Learning Experiment: A Spinning Pie Dish
	Chapter Itinerary
	2.1 Seesaws
	2.2 Wheels
	2.3 Bumper Cars
	Epilogue for Chapter 2
	Explanation: A Spinning Pie Dish
	Chapter Summary and Important Laws and Equations
CHAPTER 3 MECHANICAL OBJECTS PART 1
	Active Learning Experiment: Swinging Water Overhead
	Chapter Itinerary
	3.1 Spring Scales
	3.2 Ball Sports: Bouncing
	3.3 Carousels and Roller Coasters
	Epilogue for Chapter 3
	Explanation: Swinging Water Overhead
	Chapter Summary and Important Laws and Equations
CHAPTER 4 MECHANICAL OBJECTS PART 2
	Active Learning Experiment: High-Flying Balls
	Chapter Itinerary
	4.1 Bicycles
	4.2 Rockets and Space Travel
	Epilogue for Chapter 4
	Explanation: High-Flying Balls
	Chapter Summary and Important Laws and Equations
CHAPTER 5 FLUIDS
	Active Learning Experiment: A Cartesian Diver
	Chapter Itinerary
	5.1 Balloons
	5.2 Water Distribution
	Epilogue for Chapter 5
	Explanation: A Cartesian Diver
	Chapter Summary and Important Laws and Equations
CHAPTER 6 FLUIDS AND MOTION
	Active Learning Experiment: A Vortex Cannon
	Chapter Itinerary
	6.1 Garden Watering
	6.2 Ball Sports: Air
	6.3 Airplanes
	Epilogue for Chapter 6
	Explanation: A Vortex Cannon
	Chapter Summary and Important Laws and Equations
CHAPTER 7 HEAT AND PHASE TRANSITIONS
	Active Learning Experiment: A Ruler Thermometer
	Chapter Itinerary
	7.1 Woodstoves
	7.2 Water, Steam, and Ice
	7.3 Clothing, Insulation, and Climate
	Epilogue for Chapter 7
	Explanation: A Ruler Thermometer
	Chapter Summary and Important Laws and Equations
CHAPTER 8 THERMODYNAMICS
	Active Learning Experiment: Making Fog in a Bottle
	Chapter Itinerary
	8.1 Air Conditioners
	8.2 Automobiles
	Epilogue for Chapter 8
	Explanation: Making Fog in a Bottle
	Chapter Summary and Important Laws and Equations
CHAPTER 9 RESONANCE AND MECHANICAL WAVES
	Active Learning Experiment: A Singing Wineglass
	Chapter Itinerary
	9.1 Clocks
	9.2 Musical Instruments
	9.3 The Sea
	Epilogue for Chapter 9
	Explanation: A Singing Wineglass
	Chapter Summary and Important Laws and Equations
CHAPTER 10 ELECTRICITY
	Active Learning Experiment: Moving Water without Touching It
	Chapter Itinerary
	10.1 Static Electricity
	10.2 Xerographic Copiers
	10.3 Flashlights
	Epilogue for Chapter 10
	Explanation: Moving Water without Touching It
	Chapter Summary and Important Laws and Equations
CHAPTER 11 MAGNETISM AND ELECTRODYNAMICS
	Active Learning Experiment: A Nail and Wire Electromagnet
	Chapter Itinerary
	11.1 Household Magnets
	11.2 Electric Power Distribution
	Epilogue for Chapter 11
	Explanation: A Nail and Wire Electromagnet
	Chapter Summary and Important Laws and Equations
CHAPTER 12 ELECTROMAGNETIC WAVES
	Active Learning Experiment: A Disc in the Microwave Oven
	Chapter Itinerary
	12.1 Radio
	12.2 Microwave Ovens
	Epilogue for Chapter 12
	Explanation: A Disc in the Microwave Oven
	Chapter Summary and Important Laws and Equations
CHAPTER 13 LIGHT
	Active Learning Experiment: Splitting the Colors of Sunlight
	Chapter Itinerary
	13.1 Sunlight
	13.2 Discharge Lamps
	13.3 LEDs and Lasers
	Epilogue for Chapter 13
	Explanation: Splitting the Colors of Sunlight
	Chapter Summary and Important Laws and Equations
CHAPTER 14 OPTICS AND ELECTRONICS
	Active Learning Experiment: Magnifying Glass Camera
	Chapter Itinerary
	14.1 Cameras
	14.2 Optical Recording and Communication
	14.3 Audio Players
	Epilogue for Chapter 14
	Explanation: Magnifying Glass Camera
	Chapter Summary and Important Laws and Equations
CHAPTER 15 MODERN PHYSICS
	Active Learning Experiment: Radiation-Damaged Paper
	Chapter Itinerary
	15.1 Nuclear Weapons
	15.2 Nuclear Reactors
	15.3 Medical Imaging and Radiation
	Epilogue for Chapter 15
	Explanation: Radiation-Damaged Paper
	Chapter Summary and Important Laws and Equations
APPENDICES
	A Vectors
	B Units, Conversion of Units
Glossary
Index
EULA
                        
Document Text Contents
Page 1

H OW T H I N G S W O RK
T H E P H Y S I C S O F E V E R Y D AY L I F E

L O U I S A . B L O O M F I E L D

S I X T H E D I T I O N

Page 255

Clocks 237

amplitude steady: it’s not really a perfect harmonic oscillator. If you displace the pendulum
too far, it becomes an anharmonic oscillator—its restoring force ceases to be proportional
to its displacement from equilibrium, and its period begins to depend on its amplitude. Since
a change in period will spoil the clock’s accuracy, the pendulum’s amplitude must be kept
small and steady. That way, the amplitude has almost no effect on the pendulum’s period.

Check Your Understanding #4: Swing High, Swing Low

When pushing a child on a playground swing, you normally push her forward as she moves away from

you. What happens if you push her forward each time she moves toward you?

Answer: The amplitude of her motion will gradually decrease so that she comes to a stop.

Why: To keep her swinging, you must make up for the energy she loses to friction and air resistance.
By pushing her forward each time she moves away from you, you do work on her and increase her

energy. However, when you push her as she moves toward you, she does work on you and you extract

some of her energy. You are then slowing her down rather than sustaining her motion.

Balance Clocks
Because it relies on gravity for its restoring force, a swinging pendulum mustn’t be tilted
or moved. That’s why there are so few pendulum-based wristwatches. To make use of the
excellent timekeeping characteristics of a harmonic oscillator, a portable clock needs some
other restoring force that’s proportional to displacement but independent of gravity. It
needs a spring!

As we saw in Section 3.1, the force a spring exerts is proportional to its distortion. The
more you stretch, compress, or bend a spring, the harder it pushes back toward its equilib-
rium shape. Attach a block of wood to the free end of a spring, stretch it gently, and let go,
and you’ll fi nd you have a harmonic oscillator with a period determined only by the stiff-
ness of the spring and the block’s mass (Fig. 9.1.5). Since the period of a harmonic oscil-
lator doesn’t depend on the amplitude of its motion, the block oscillates steadily about its
equilibrium position and makes an excellent timekeeper.

Unfortunately, gravity complicates this simple system. Although gravity doesn’t
alter the block’s period, it does shift the block’s equilibrium position downward. That

Equilibrium

Acceleration

Velocity

Force

Fig. 9.1.5 A metal
cylinder attached to a

spring is a harmonic

oscillator, shown here in

a time sequence (top to

bottom). The oscillator’s

period is determined only

by the stiffness of the

spring and the cylinder’s

mass.

Page 256

238 CHAPTER 9 Resonance and Mechanical Waves

shift is a problem for a clock that might be tilted sometimes. However, there’s another
spring-based timekeeper that marks time accurately in any orientation or location. This
ingenious device, used in most mechanical clocks and watches, is called a balance ring
or simply a balance.

A balance ring resembles a tiny metal bicycle wheel, supported at its center of mass/
gravity by an axle and a pair of bearings (Fig. 9.1.6). Any friction in the bearings is exerted
so close to the ring’s axis of rotation that it produces little torque and the ring turns
extremely easily. Moreover, the ring pivots about its own center of gravity so that its weight
produces no torque on it. In keeping with its name, the balance is balanced.

The only thing exerting a torque on the balance ring is a tiny coil spring. One end of
this spring is attached to the ring, while the other is fi xed to the body of the clock. When
the spring is undistorted, it exerts no torque on the ring and the ring is in equilibrium. If
you rotate the ring either way, however, torque from the distorted spring will act to restore
it to its equilibrium orientation. Since this restoring torque is proportional to the ring’s
rotation away from a stable equilibrium, the balance ring and coil spring form a harmonic
oscillator!

Because of the rotational character of this harmonic oscillator, its period depends on
the torsional stiffness of the coil spring, that is, on how rapidly the spring’s torque
increases as you twist it, and on the balance ring’s rotational mass. Since the balance
ring’s period doesn’t depend on the amplitude of its motion, it keeps excellent time. Also,
because gravity exerts no torque on the balance ring, this timekeeper works anywhere and
in any orientation.

The rest of a balance clock is similar to a pendulum clock (Fig. 9.1.7). As the balance
ring rocks back and forth, it tips a lever that controls the rotation of a toothed wheel. An
anchor attached to the lever allows the toothed wheel to advance one tooth for each com-
plete cycle of the balance ring’s motion. Gears connect the toothed wheel to the clock’s
hands, which slowly advance as the wheel turns.

Because the balance clock is portable, it can’t draw energy from a weighted cord.
Instead, it has a main spring that exerts a torque on the toothed wheel. This main spring is
a coil of elastic metal that stores energy when you wind the clock. Its energy keeps the
balance ring rocking steadily back and forth and also turns the clock’s hands. Since the

Equilibrium

Ring

Coil spring

Angular
velocity

Torque

Angular
acceleration

Fig. 9.1.6 A small wheel
attached to a coil spring is

a harmonic oscillator known

as a balance ring, shown

here in a time sequence

(top to bottom). Its period

is determined only by the

stiffness of the coil spring

and the rotational mass of

the wheel.

Balance ring Coil spring

Jewel bearing

C
o
u
rt

e
s
y
L

o
u
B

lo
o
m

fi
e
ld

Fig. 9.1.7 The balance ring in this
antique French carriage clock twists back

and forth rhythmically under the infl uence

of the spiral spring near its center. The

tiny ruby bearings that support the ring

minimize friction and permit this clock to

keep very accurate time.

Page 510

492 Index

U
Ultraviolet light, 355
Underwater sound, 252
Uniform circular motion, 87
Unstable equilibrium, 99
Uranium (U), 432–434, 440–442, 443
235 uranium (U), 432–434, 439, 440, 443
238 uranium (U), 432–433, 443

V
Valence band, 380
Valence level, 380
Van de Graaff generator, 274
Vaporization, 187
Vector fi eld, 279
Vector quantity, 3, 43
Velocity

angular, 36
average, 16
defi ned, 3–4, 8
escape, 111
exhaust, 106
of falling ball, 15–16
forward, 21
initial, 15, 19
present, 15
SI unit of, 11
terminal, 158
translational, 40
wave, 251

Vertical polarization, 337
Vibrational nodes, 85
Vibrations

defi ned, 239
drum, 249–250, 252–253
organ pipe, 247–248
overtone, 249
sympathetic, 246
turning into sound, 252–253
violin string, 242–246

Viewfi nders, 399–401
Views, 10
Violin bridge, 253
Violin strings. See also Musical instruments

bowing and plucking, 245–246
harmonics, 244–245
perpendicular oscillation, 243
tension, 242
turning vibrations into sound, 253

Virtual images, 400, 401
Viscosity

defi ned, 144
effect of, 145–146
of fl uids, 144
water, 144

Viscous drag, 154
Viscous forces, 144, 145, 147
Visible light, 354
Volt, 273
Voltage

amplifi er, 421
battery, 290
on conducting object, 282

defi ned, 273
drop, 293
equation, 273
in fl ashlights, 293–294
lightening, 273
rise, 294
root mean square (RMS), 316
SI unit, 273
transformer, changing, 322–324

Voltage gradients, 282–283
Voltage per meter, 283
Volume

air, 121
SI unit, 123

Vortex, 152, 166
Vortex cannon, 142–143, 171

W
Wake, 153
Wake force, 159
Walking, 12
Warmth. See also Insulation

by controlling thermal radiation, 200–201
by impeding convection, 195–196
by limiting thermal conduction, 193–195
on a windy day, 145

Warm-up pitches, 175
Water. See also Ice; Steam

boiling, 189–191
evaporating, 187–188
experiments, 184
freezing, 186
how it works summary, 206
as incompressible, 133
as liquid, 184, 185
moving, 134–136, 138–140
moving without touching, 266–267, 300
overview, 184
phases of, 184–185
relative humidity and, 188
steady-state fl ow, 135
streamline, 135
in strong electric fi eld, 344
superheated, 191
viscosity, 144

Water distribution
experiments, 131
gravity and, 136–140
how it works summary, 141
moving water and, 134–136
overview, 131
pressure and, 131–134
requirements, 131

Water hammer, 152
Water power, 139
Water pressure

in bent house, 147, 148
dynamic variation in, 132
energy and, 134–136
in the garden, 132
gravity and, 136–138
speed and, 149
static variation in, 132

up or out, 140
in water distribution, 131–132
with water pumps, 133–134

Water pumps, 133–134
Watts, 56
Watts, William, 17
Wave velocity, 251
Wavelengths, 197, 251
Wave-particle duality, 366
Waves. See also Tides

beneath, 259
breaking, 261
capillary, 256
dispersion, 259, 263
electron standing, 367–368
frequency of, 258
gravity, 256
interference, 263
out of phase, 263
in phase, 263
phenomena summary, 263
refl ection, 260, 263
refraction, 260, 263
seiches, 256
at shore, 260–262
slope of sea bottom and, 261
standing, 257, 258
structure of, 258–259
surface, 256
tsunamis, 259

Weak force, 454
Weight

apparent, 90
feeling of, 90
friction and, 51
gravity and, 13

“Weightlessness,” 111
Wheels

experiments, 49
fi ling cabinet movement and, 53–55
friction and, 49–53
how they work summary, 70–71
overview, 48
power and, 56–57
rollers, 54, 55
sliding friction, 54
static friction, 54, 55

Wind
heat and, 180
heat loss and, 196
on open road, 152
urban, 152

Windows, insulating, 203–204
Windscale reactor, 444
Wings, airplane

airfoil, 161
angle of attack, 164–165
blunt, 165
leading edge, 161
lift production, 162–165
stalling, 165–167
streamlined wing, 162
trailing edge, 161
vortex, 166

Page 511

Index 493

Woodstoves
burning log, 174–175
conduction, 179
convection, 180
experiments, 174
how they work summary, 206
open fi res and, 178
overview, 174
radiation, 180–182
thermal energy, 174–175
warming the room, 182–183

Work
calculating, 26–27, 28
defi ned, 25, 27
equation, 26
thermal energy and, 51

Wrapper, negatively charged,
271

Wrench magnetism, 310
Wright, Orville and Wilber, 168

X
Xerographic copiers

capacitors, 286–287
charging by induction, 285–286
corona discharge, 278–279,

284–285
electric fi elds, 279–280
experiments, 276
getting ready to use, 285–286
how they work summary, 301
overview, 276
photoconductors, 276–277, 278
precharging, 277
sticky copies, 278

test charges, 279–280
xerography, 276–278

X-ray fl uorescence, 449
X-rays. See also Medical imaging and

radiation
aluminum and, 452
characteristic, 449–450
defi ned, 449
for imaging, 451–452
making, 449–450
overview, 448–449
for therapy, 452–453

Z
Zero net force, 75
Zeroth law of thermodynamics, 210
Zoom lenses, 399

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