Physics For Dummies

Physics For Dummies
By Steven Holzner
Contents at a Glance
Introduction .1
Part I: Putting Physics into Motion 5
Chapter 1: Using Physics to Understand Your World 7
Chapter 2: Understanding Physics Fundamentals .13
Chapter 3: Exploring the Need for Speed 25
Chapter 4: Following Directions: Which Way Are You Going? 43
Part II: May the Forces of Physics Be with You .61
Chapter 5: When Push Comes to Shove: Force 63
Chapter 6: What a Drag: Inclined Planes and Friction .81
Chapter 7: Circling around Circular Motions and Orbits 99
Part III: Manifesting the Energy to Work 117
Chapter 8: Getting Some Work out of Physics 119
Chapter 9: Putting Objects in Motion: Momentum and Impulse 137
Chapter 10: Winding Up with Angular Kinetics 153
Chapter 11: Round and Round with Rotational Dynamics 173
Chapter 12: Springs-n-Things: Simple Harmonic Motion 189
Part IV: Laying Down the Laws of Thermodynamics .205
Chapter 13: Turning Up the Heat with Thermodynamics .207
Chapter 14: Here, Take My Coat: Heat Transfer in Solids and Gases .219
Chapter 15: When Heat and Work Collide: The Laws of Thermodynamics 235
Part V: Getting a Charge out of Electricity
and Magnetism .251
Chapter 16: Zapping Away with Static Electricity 253
Chapter 17: Giving Electrons a Push with Circuits 271
Chapter 18: Magnetism: More than Attraction .287
Chapter 19: Keeping the Current Going with Voltage 305
Chapter 20: Shedding Some Light on Mirrors and Lenses 323Part VI: The Part of Tens .339
Chapter 21: Ten Amazing Insights on Relativity .341
Chapter 22: Ten Wild Physics Theories .349
Glossary .355
Index .361Table of Contents
Introduction 1
About This Book .1
Conventions Used in This Book .2
What You’re Not to Read .2
Foolish Assumptions .2
How This Book Is Organized .2
Part I: Putting Physics into Motion 3
Part II: May the Forces of Physics Be with You 3
Part III: Manifesting the Energy to Work 3
Part IV: Laying Down the Laws of Thermodynamics .3
Part V: Getting a Charge out of Electricity and Magnetism .3
Part VI: The Part of Tens .4
Icons Used in This Book 4
Where to Go from Here 4
Part I: Putting Physics into Motion .5
Chapter 1: Using Physics to Understand Your World . . . . . . . . . . . . . . .7
What Physics Is All About .7
Observing Objects in Motion 8
Absorbing the Energy Around You 9
Feeling Hot but Not Bothered .10
Playing with Charges and Magnets 10
Preparing for the Wild, Wild Physics Coming Up .11
Chapter 2: Understanding Physics Fundamentals . . . . . . . . . . . . . . . . .13
Don’t Be Scared, It’s Only Physics .14
Measuring the World Around You and Making Predictions 15
Don’t mix and match: Keeping physical units straight 16
From meters to inches and back again:
Converting between units 17
Eliminating Some Zeros: Using Scientific Notation 20
Checking the Precision of Measurements .21
Knowing which digits are significant .21
Estimating accuracy .22
Arming Yourself with Basic Algebra 23
Tackling a Little Trig 23Chapter 3: Exploring the Need for Speed . . . . . . . . . . . . . . . . . . . . . . . .25
Dissecting Displacement .26
Examining axes .27
Measuring speed 28
Speed Specifics: What Is Speed, Anyway? .29
Reading the speedometer: Instantaneous speed .30
Staying steady: Uniform speed .30
Swerving back and forth: Nonuniform motion .30
Busting out the stopwatch: Average speed 31
Pitting average speed versus uniform motion 31
Speeding Up (or Down): Acceleration .33
Defining acceleration .33
Determining the units of acceleration .33
Positive and negative acceleration 35
Average and instantaneous acceleration 36
Uniform and nonuniform acceleration 37
Relating Acceleration, Time, and Displacement 37
Not-so-distant relations .38
Equating more speedy scenarios .39
Linking Speed, Acceleration, and Displacement 40
Chapter 4: Following Directions: Which Way Are You Going? . . . . . .43
Conquering Vectors .43
Asking for directions: Vector basics 44
Putting directions together: Adding vectors 45
Taking distance apart: Subtracting vectors 46
Waxing Numerical on Vectors .47
Breaking Up Vectors into Components .49
Finding vector components given magnitudes and angles .49
Finding magnitudes and angles given vector components .51
Unmasking the Identities of Vectors 53
Displacement is a vector .54
Velocity is another vector .54
Acceleration: Yep, another vector 55
Sliding Along on Gravity’s Rainbow: A Velocity Exercise 57
Part II: May the Forces of Physics Be with You .61
Chapter 5: When Push Comes to Shove: Force . . . . . . . . . . . . . . . . . . .63
Forcing the Issue 63
For His First Trick, Newton’s First Law of Motion .64
Getting it going: Inertia and mass 65
Measuring mass 65
Ladies and Gentlemen, Newton’s Second Law of Motion .66
Naming units of force .67
Gathering net forces .67
viii Physics For DummiesNewton’s Grand Finale: The Third Law of Motion .72
Tension shouldn’t cause stiff necks:
Friction in Newton’s third law .73
Analyzing angles and force in Newton’s third law .75
Finding equilibrium 77
Chapter 6: What a Drag: Inclined Planes and Friction . . . . . . . . . . . . .81
Don’t Let It Get You Down: Dealing with Gravity .81
Leaning Vertical: An Inclined Plane .82
Figuring out angles the easy way .83
Playing with acceleration 84
Getting Sticky with Friction 85
Calculating friction and the normal force .86
Conquering the coefficient of friction 86
Understanding static and kinetic friction 87
Handling uphill friction 89
Determining How Gravity Affects Airborne Objects .94
Going up: Maximum height .94
Floating on air: Hang time .95
Going down: Factoring the total time 95
Firing an object at an angle .96
Chapter 7: Circling around Circular Motions and Orbits . . . . . . . . . . .99
Staying the Course: Uniform Circular Motion 100
Changing Direction: Centripetal Acceleration 101
Controlling velocity with centripetal acceleration 101
Finding the magnitude of the centripetal acceleration .102
Pulling Toward the Center: Centripetal Force 102
Negotiating Curves and Banks: Centripetal Force through Turns .104
Getting Angular: Displacement, Velocity, and Acceleration .106
Dropping the Apple: Newton’s Law of Gravitation 108
Deriving the force of gravity on the earth’s surface 109
Using the law of gravitation to examine circular orbits 110
Looping the Loop: Vertical Circular Motion .113
Part III: Manifesting the Energy to Work 117
Chapter 8: Getting Some Work out of Physics . . . . . . . . . . . . . . . . . . .119
Work: It Isn’t What You Think .119
Working on measurement systems 120
Pushing your weight 120
Taking a drag .121
Considering Negative Work .122
Getting the Payoff: Kinetic Energy .123
Breaking down the kinetic energy equation .125
Putting the kinetic energy equation to use .126
Calculating kinetic energy by using net force .127
Table of Contents ixEnergy in the Bank: Potential Energy 128
Working against gravity .129
Converting potential energy into kinetic energy 130
Choose Your Path: Conservative versus Nonconservative Forces .131
Up, Down, and All Around: The Conservation of Mechanical Energy 132
Determining final velocity with mechanical energy .134
Determining final height with mechanical energy 134
Powering Up: The Rate of Doing Work 135
Common units of power 135
Alternate calculations of power .136
Chapter 9: Putting Objects in Motion: Momentum and Impulse . . . .137
Looking at the Impact of Impulse .137
Gathering Momentum 139
The Impulse-Momentum Theorem: Relating Impulse and
Momentum 140
Shooting pool: Finding impulse and momentum 141
Singing in the rain: An impulsive activity 142
When Objects Go Bonk: Conserving Momentum .143
Measuring velocity with the conservation of momentum 145
Measuring firing velocity with the conservation of momentum .146
When Worlds (or Cars) Collide: Elastic and Inelastic Collisions .148
When objects bounce: Elastic collisions .148
When objects don’t bounce: Inelastic collisions 149
Colliding along a line 149
Colliding in two dimensions 151
Chapter 10: Winding Up with Angular Kinetics . . . . . . . . . . . . . . . . . .153
Going from Linear to Rotational Motion .153
Understanding Tangential Motion .154
Finding tangential speed .154
Finding tangential acceleration 156
Finding centripetal acceleration .156
Applying Vectors to Rotation .158
Calculating angular velocity 158
Figuring angular acceleration .159
Twisting and Shouting: Torque .160
Mapping out the torque equation 162
Understanding lever arms .162
Figuring out the torque generated .164
Recognizing that torque is a vector .165
No Wobbling Allowed: Rotational Equilibrium .166
Hanging a flag: A rotational equilibrium problem 167
Ladder safety: Introducing friction into rotational equilibrium 168
Chapter 11: Round and Round with Rotational Dynamics . . . . . . . . .173
Rolling Up Newton’s Second Law into Angular Motion .173
Converting tangential acceleration to angular acceleration 175
Factoring in the moment of inertia 175
x Physics For DummiesExamining Moments of Inertia 176
CD players and torque: An inertia example 177
Angular acceleration and torque: Another inertia example .179
Wrapping Your Head around Rotational Work and Kinetic Energy .180
Doing some rotational work 180
Tracking down rotational kinetic energy 182
Measuring rotational kinetic energy on a ramp .183
Can’t Stop This: Angular Momentum .185
Reviewing the conservation of angular momentum 186
Satellite orbits: A conservation
of angular momentum example 186
Chapter 12: Springs-n-Things: Simple Harmonic Motion . . . . . . . . .189
Hooking Up with Hooke’s Law 189
Keeping springs stretchy .190
Deducing that Hooke’s law is a restoring force 191
Moving with Simple Harmonic Motion 191
Examining basic horizontal and vertical simple
harmonic motion 192
Diving deeper into simple harmonic motion 193
Finding the angular frequency of a mass on a spring 200
Factoring Energy into Simple Harmonic Motion 202
Swinging with Pendulums .203
Part IV: Laying Down the Laws of Thermodynamics .205
Chapter 13: Turning Up the Heat with Thermodynamics . . . . . . . . . .207
Getting into Hot Water .208
When the thermometer says Fahrenheit .208
When the thermometer says Celsius .208
When the thermometer says Kelvin 209
The Heat Is On: Linear Expansion 210
Deconstructing linear expansion .212
Workin’ on the railroad: A linear expansion example 212
The Heat Continues On: Volume Expansion .213
Going with the Flow (of Heat) .214
Changing Phases: When Temperatures Don’t Change 216
Breaking the ice with phase changes .217
Understanding latent heat .218
Chapter 14: Here, Take My Coat: Heat Transfer
in Solids and Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219
Boiling Water: Convection .219
Too Hot to Handle: Conduction 220
Examining the properties that affect conduction
to find the conduction equation .221
Applying the heat-transferred-by-conduction equation 223
Table of Contents xiEmitting and Absorbing Light: Radiation 224
You can’t see radiation, but it’s there 225
Radiation and blackbodies 226
Crunching Avogadro’s Number 228
Forging the Ideal Gas Law .229
Gas pressure: An ideal gas law example 231
Boyle’s Law and Charles’ Law: Alternative expressions
of the ideal gas law .231
Tracking Ideal Gas Molecules .232
Predicting air molecule speed 232
Calculating kinetic energy in an ideal gas .233
Chapter 15: When Heat and Work Collide:
The Laws of Thermodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .235
Gaining Thermal Equilibrium: The Zeroth Law of Thermodynamics 235
Conserving Heat and Energy: The First Law of Thermodynamics 236
Calculating conservation .237
Examining isobaric, isochoric, isothermal,
and adiabatic processes, oh my! 238
Figuring out specific heat capacities .245
When Heat Flows: The Second Law of Thermodynamics .246
Putting heat to work: Heat engines 246
Evaluating heat’s work: Heat engine efficiency 247
Carnot says you can’t have it all 248
Going Cold: The Third (and Absolute Last) Law of Thermodynamics 250
Part V: Getting a Charge out of Electricity
and Magnetism .251
Chapter 16: Zapping Away with Static Electricity . . . . . . . . . . . . . . .253
Plus and Minus: Electron and Proton Charges .253
Push and Pull: Electric Forces 254
Charging it to Coulomb’s law 255
Bringing objects together 255
Calculating the speed of electrons .256
Looking at forces between multiple charges 256
Influence at a Distance: Electric Fields 258
Coming from all directions: Electric fields
from point charges .259
Charging nice and steady: Electric fields
in parallel plate capacitors 261
Electric Potential: Cranking Up the Voltage 262
Calculating electric potential energy .263
Realizing the potential in voltage .264
Discovering that electric potential is conserved .265
Finding the electric potential of point charges 266
Getting fully charged with capacitance .269
xii Physics For DummiesChapter 17: Giving Electrons a Push with Circuits . . . . . . . . . . . . . . .271
Electrons on the March: Current 271
Defining current 272
Calculating the current in batteries .272
Giving You Some Resistance: Ohm’s Law 273
Determining current flow 273
Examining resistivity 274
Powering Up: Wattage 275
Flowing from One to the Other: Series Circuits .275
Splitting the Current: Parallel Circuits 276
Looping Together Electricity with Kirchoff’s Rules .278
Implementing the loop rule .279
Using multiple-loop circuits 280
Conquering Capacitors in Parallel and Series Circuits .283
Capacitors in parallel circuits .283
Capacitors in series circuits .284
Putting Together Resistors and Capacitors: RC Circuits 285
Chapter 18: Magnetism: More than Attraction . . . . . . . . . . . . . . . . . . .287
Finding the Source of Attraction 288
Forcing a Moving Charge .289
Figuring the Quantitative Size of Magnetic Forces 290
Moving in Orbits: Charged Particles in Magnetic Fields .292
Magnetic fields do no work . . 292
. . . but they still affect moving charged particles 293
Pushing and Pulling Currents .295
Forces on currents .295
Torques on currents .296
Identifying the Magnetic Field from a Wire .298
Centering on Current Loops .300
Achieving a Uniform Magnetic Field with Solenoids .302
Chapter 19: Keeping the Current Going with Voltage . . . . . . . . . . . . .305
Inducing EMF (Electromagnetic Frequency) 305
Moving a conductor in a magnetic field to cause voltage .306
Inducing voltage over a certain area .307
Factoring In the Flux with Faraday’s Law 308
Getting the Signs Right with Lenz’s Law .310
Figuring out Inductance 312
Examining Alternating Current Circuits 313
Picturing alternating voltage 314
Unearthing root mean square current and voltage 314
Leading with capacitors 315
Lagging with inductors 318
Handling the Triple Threat: RCL Circuits 321
Table of Contents xiiiChapter 20: Shedding Some Light on Mirrors and Lenses . . . . . . . . .323
All about Mirrors (srorriM tuoba llA) 323
When Light Gets Bendy .324
Refracting light with Snell’s Law .324
Examining water at apparent depths .325
All Mirrors and No Smoke .327
Expanding with concave mirrors .327
Contracting with convex mirrors .332
Seeing Clearly with Lenses 333
Expanding with converging lenses .334
Contracting with diverging lenses 337
Part VI: The Part of Tens 339
Chapter 21: Ten Amazing Insights on Relativity . . . . . . . . . . . . . . . . . .341
Nature Doesn’t Play Favorites 341
The Speed of Light Is Constant, No Matter How Fast You Go 342
Time Dilates at High Speeds .343
Space Travel Ages You Less 343
Length Contracts at High Speeds .344
E = mc2: The Equivalence of Matter and Energy .345
Matter Plus Antimatter Equals Boom 345
The Sun Is Radiating Away Mass 346
The Speed of Light Is the Ultimate Speed .346
Newton Is Still Right .347
Chapter 22: Ten Wild Physics Theories . . . . . . . . . . . . . . . . . . . . . . . . .349
You Can Measure a Smallest Distance .349
There Might Be a Smallest Time .350
Heisenberg Says You Can’t Be Certain 350
Black Holes Don’t Let Light Out .351
Gravity Curves Space 351
Matter and Antimatter Destroy Each Other .352
Supernovas Are the Most Powerful Explosions .353
The Universe Starts with the Big Bang and Ends with the Gnab Gib 353
Microwave Ovens Are Hot Physics 353
Physicists May Not Have Physical Absolute Measures .354
Glossary .355
Index 361
xiv Physics For Dummies .
360 Physics For Dummies• A •
absolute measures physics
theory, 354
absolute zero, 209–210, 250
absorbing energy, 9–10
acceleration
about, 33, 66–67, 355
average, 36
circular motion, 106–108
friction, 91–92
gravity, 84–85
inertia, 179–182
instantaneous, 36
negative, 35–36
nonuniform, 37
positive, 35–36
simple harmonic motion,
198–200
speed, 40–41
tangential, 156
torque, 179–182
uniform, 37
units, 33–35
vectors, 55–57
addition, 22
adiabatic, 243–244, 355
advanced moments of
inertia, 175–177
air molecule speed, 232–233
air pressure measurement,
232
airborne objects gravity,
94–97
algebra, 23
alternate calculations, power,
136
alternating current (A/C)
about, 313, 355
capacitors, 315–318
inductors, 318–320
RCL circuits, 321–322
real values, 317–318
root mean square current
and voltage, 314–315
viewing, 314
alternating voltage, 355
aluminum resistivity, 275
ampere, 355
analogs, 174
angle of incidence, 323
angle of reflection, 323
angles
gravity, 83–84
third law of motion, 75–77
vectors, 51–53
angular acceleration
about, 159–160, 355
converting tangential
acceleration to, 175
angular displacement, 355
angular frequency of mass of
spring, 200–202
angular momentum
about, 355
conservation, 186
rotational motion, 173–176
satellite orbits, 186–187
angular velocity, 158–159, 355
antimatter, 345–346
antimatter destroying each
other, physics theory,
352
arrows, 44–45
atomic units, 228
atoms, 253–254
attraction source,
magnetism, 288–289
average acceleration, 36
average motion speed, 31–32
average speed, 31
Avogadro’s Number
about, 355
heat transfer, 228–229
axes displacement, 27–28
• B •
battery current, 272–273
Big Bang physics theory, 353
black holes physics theory,
351
blackbodies
about, 355
radiation, 226–227
blanket heat, 214
Boltzmann’s constant, 230,
355
bounce, 149
Boyle’s law, 231
brass thermal conductivity,
223
• C •
calculating
electric potential energy,
263–264
energy conservation,
237–238
kinetic energy with net
force, 127–128
capacitance
about, 355
electric potential energy,
269–270
capacitors
about, 283, 355
alternating current (A/C),
315–318
electric potential energy,
269–270
parallel circuits, 283–284
series circuits, 284
carbon resistivity, 275
Carnot engine, 248–250
Carnot’s principle, 249
Celsius scale, 208–209
Indexcentering current loops,
magnetism, 300–302
centimeter-gram-second
(CGS) system
measurement, 15–16,
19–20
centripetal acceleration,
about, 156–158, 355
controlling velocity,
101–102
magnitude, 102
centripetal force, 102–103,
356
CGS system, 356
charged particles in
magnetic fields,
magnetism, 292–295
Charles’ law, 231
circular motion
about, 99–100
acceleration, 106–108
centripetal acceleration,
101–102
centripetal force, 102–103
circular orbits, 110–113
curves and banks, 104–106
displacement, 106–108
gravity, 109–110
Kepler’s laws of orbiting
bodies, 113
Newton’s law of gravitation,
108–113
satellite period, 112–113
turns, 104–106
uniform, 100
velocity, 106–108
vertical, 113–115
closed system, 144
coefficient of friction, 86–87
cold, 10
collisions
along lines, 149–151
heavier mass, 149–150
lighter mass, 150–151
two dimensions, 151–152
component weight friction, 90
components, vectors, 49–53
concave mirrors, 327–332,
356
conduction
about, 220, 356
equation, 221–223
thermal conductivity,
222–223
conservation
angular momentum, 186
electric potential energy,
265–266
energy, 356
mechanical energy, 132
conservative force versus
nonconservative force,
work, 131–132
constant heat, 243–244
controlling velocity,
centripetal acceleration,
101–102
convection, 219–220, 356
convective motion, 220
converging lenses, 334–337,
356
conversions
Kelvin system, 210
kinetic energy into
potential energy, 130
measurement units, 17–20
tangential acceleration to
angular acceleration, 175
convex mirrors, 332–333, 356
copper
resistivity, 275
thermal conductivity, 223
cosine, 24
Coulomb’s law, 254, 255, 356
current, 272, 356
current flow, 273–274
curves and banks, circular
motion, 104–106
• D •
deceleration, 33
deconstructing linear
expansion, 212
density, 356
direct current, 356
directions. See vectors
displacement
about, 26, 37–40, 356
axes, 27–28
calculating, 68–71
circular motion, 106–108
speed, 40–41
speed measurement, 28–29
vectors, 54
distance, friction, 92–93
diverging lenses, 337–338, 356
division, 21
drag, work, 121–122
• E •
Einstein, Albert, 11, 64,
341–348, 351
elastic collisions, 148, 356
elastic limit, periodic motion,
190
elastic potential energy,
202–203
elasticity, periodic motion,
189–191
electric fields
about, 258–259, 356
point charges, 259–260
positive charges, 258–259
test charges, 259–260
electric forces, 254–257
electric potential energy
calculating, 263–264
capacitance, 269–270
conservation, 265–266
point charges, 266–268
static electricity, 262–270
voltage, 264–265
electricity, 10–11
electromagnetic frequency
(EMF)
about, 305–308
alternating current (A/C),
313–320
Faraday’s law, 308–310
inducing voltage, 307–308
inductance, 312–313
Lenz’s law, 310–312
magnetic flux, 308–310
moving conductor in
magnetic field, 306–307
362 Physics For Dummieselectromotive force, 271–272,
356
electron charges
Coulomb’s law, 255
electron speed, 256
multiple charges, 256–257
static electricity, 253–254
electrons
about, 271
battery current, 272–273
capacitors, 283–285
current, 272
electromotive force,
271–272
Kirchoff’s rules, 278–282
Ohm’s law, 273–275
parallel circuits, 276–278
RC circuits, 285–286
series circuits, 275–276
speed, 256
wattage, 275
electrostatic potential, 356
emissivity, 356
energy
about, 356
absorbing, 9–10
energy conservation
calculating, 237–238
thermodynamics, 236–246
equal vectors, 45
equation
conduction, 221–223
kinetic energy, 125–127
torque, 162
equilibrium
about, 166
third law of motion, 77–79
equilibrium point, 192–193
equivalence of matter and
energy, 345
estimating accuracy,
measurement, 22
• F •
factoring energy into simple
harmonic motion,
202–203
Fahrenheit, Daniel Gabriel,
208
Fahrenheit scale, 208–209
farad, 357
Faraday’s law, 308–310
firing object at angles,
gravity, 96–97
firing velocity, momentum,
146–148
first law of thermodynamics
adiabatic, 243–244
isobaric, 238–240
isochoric, 240–241
isothermal, 241–243
molar specific heat
capacity, 245–246
specific heat capacities,
245–246
thermodynamics, 236–246
force
about, 63–64
calculating displacement,
68–71
calculating net force, 71
on currents, 295–296
friction, 90–91
inertia and mass, 65–66
naming units, 67
net force, 67–72
FPS system, 357
frequency, 357
friction
acceleration, 91–92
coefficient, 86–87
component weight, 90
distance, 92–93
force, 90–91
gravity, 85–93
kinetic, 87–89
normal force, 86
rotational equilibrium,
168–171
static, 87–89
third law of motion, 73–75
uphill, 89–93
fulcrum torque, 161
• G •
gamma waves, 352
gas pressure, 231
General Theory of Relativity,
351
generated torque, 164–165
glass thermal conductivity,
223
gold resistivity, 275
gravity
about, 81–82
acceleration, 84–85
airborne objects, 94–97
angles, 83–84
circular motion, 109–110
firing object at angles,
96–97
friction, 85–93
hang time, 95
inclined planes, 82–85
maximum height, 94–95
potential energy, 129–130
total time, 95–96
vectors, 57–59
gravity curves space physics
theory, 351–352
• H •
hang time, gravity, 95
heat, 10, 214–216
heat capacity, 357
heat conductivity, 232–234
heat engines, 246–248
heat transfer
about, 219
Avogadro’s Number,
228–229
conduction, 220–224
convection, 219–220
convective motion, 220
ideal gas law, 229–232
radiation, 224–227
thermals, 220
heavier mass collisions,
149–150
height, mechanical energy,
134–135
Heisenberg Uncertainty
Principle physics theory,
350–351
henry, 357
hertz, 357
Index 363Hooke’s law
about, 189
elastic limit, 190
elasticity, 189–191
ideal spring, 190
restoring force, 191
horizontal simple harmonic
motion, 192–193
• I •
ideal gas law
Boyle’s law, 231
Charles’ law, 231
gas pressure, 231
heat transfer, 229–232
ideal gas molecules
about, 232
air molecule speed, 232–233
kinetic energy, 233–234
ideal gases, 229
ideal spring periodic motion,
190
impulse, 137–139, 357
impulse-momentum theorem
about, 140
equation, 141–142
inclined planes, gravity, 82–85
index of refraction, 357
induced EMF, 305
induced magnetic field, 311
inducing voltage,
electromagnetic
frequency (EMF),
307–308
inductance, electromagnetic
frequency (EMF),
312–313
inductors, alternating
current (A/C), 318–320
inelastic collisions, 148, 357
inertia
acceleration and torque,
179–182
advanced moments of,
175–177
force, 65–66
rotational kinetic energy,
182–183
rotational motion, 175–182
torque, 177–178
inertial frame, 357
inertial reference frame,
Theory of Special
Relativity, 341–342
instantaneous acceleration,
36
instantaneous speed, 30
inverse sine, 24
isobaric, 238–240, 357
isochoric, 240–241, 357
isolated system, 144
isothermal, 241–243, 357
isotherms, 243
• J •
Joules, 120, 357
junction rule, 278
• K •
Kelvin system
conversions, 210
thermodynamics, 209–210
Kelvins, 210, 357
Kepler’s laws of orbiting
bodies, 113
kilograms, 357
kinematics, 137, 357
kinetic energy
about, 9, 357
calculating with net force,
127–128
converting into potential
energy, 130
equation, 125–127
ideal gas molecules,
233–234
rotational motion, 180–185
work, 123–128
kinetic friction, 87–89, 357
Kirchoff’s rules
about, 278
junction rule, 278
loop rule, 278–280
multiple-loop circuits,
280–282
• L •
latent heat
about, 357
thermodynamics, 218
Web sites, 218
law of conservation of
momentum, 357
law of motion, 64–66
law of reflection, 323
length contracts at high
speeds, 344–345
lenses
about, 333
converging, 334–337
diverging lenses, 337–338
magnification, 336–337
Lenz’s law, 310–312
lever arm, torque, 162–164
light
radiation, 224–227
refracting, 324–325
Snell’s law, 324–325
speed, 64, 326–327, 342,
346–347
lighter mass collisions,
150–151
linear expansion
about, 210–211
deconstructing, 212
example, 212–213
linear momentum, 357
linear motion to rotational
motion, 153–154
lines, collisions along,
149–151
loop rule, 278–280
• M •
magnetic fields
about, 358
from wire, 298–300
magnetic flux,
electromagnetic
frequency (EMF),
308–310
magnetic poles, 288
364 Physics For Dummiesmagnetism
about, 10–11, 287
attraction source, 288–289
centering current loops,
300–302
charged particles in
magnetic fields, 292–295
forces on currents, 295–296
magnetic field from wire,
298–300
magnetic poles, 288
moving charge, 289–290
moving in orbits, 292–295
north pole, 288
permanent magnets, 288
pushing and pulling
currents, 295–298
quantitative size of
magnetic forces, 290–292
south pole, 288
torques on currents,
296–298
uniform magnetic field with
solenoids, 302–303
magnification
lenses, 336–337
mirrors, 332
magnitudes
about, 358
centripetal acceleration,
102
vectors, 43, 49–53
mass
about, 358
force, 65–66
math, physics, and, 14
matter
destroy each other physics
theory, 352
Theory of Special Relativity,
345–346
maximum height, gravity,
94–95
measure smallest distance
physics theory, 349–350
measurement
about, 15–16
centimeter-gram-second
(CGS) system, 15–16,
19–20
converting units, 17–20
estimating accuracy, 22
meter-kilogram-second
(MKS) system, 15–16,
19–20
precision, 21–22
scientific notation, 20
significant digits, 21–22
units, 15–16
work, 120
measurment
air pressure, 232
water pressure, 232
mechanical energy
conservation, 132
height, 134–135
velocity, 134
metal radiant heating, 226
meter-kilogram-second
(MKS) system, 15–16,
19–20, 358
mgh, 130
microwave ovens physics
theory, 353–354
mirrors
about, 323–324, 327
concave, 327–332
convex, 332–333
magnification, 332
models, 14
molar specific heat capacity,
245–246
mole, 228
molecular mass, 229
moment arm, torque, 162
moment of inertia, 358
momentum
about, 139–140
final total, 145
firing velocity, 146–148
rain, 142–143
velocity, 145–146
movement
displacement, 26–29
distance, 26–29
objects, 8–9
moving charge, 289–290
moving conductor in
magnetic field,
electromagnetic
frequency (EMF),
306–307
moving in orbits, magnetism,
292–295
multiple charges, 256–257
multiple-loop circuits,
280–282
multiplication, 21
• N •
naming units force, 67
National Magnet Lab, MIT,
298
near-zero, 250
negative
acceleration, 35–36
work, 122–123
negative angular
acceleration, 160
net force
about, 66, 67–72
calculating, 71
net negative charge, 254
net positive charge, 254
neutron star physics theory,
351
Newton, Isaac
about, 63–64, 347–348, 351,
358
law of gravitation, 108–113
law of motion, 64–66
second law of motion,
66–72, 173–176
third law of motion, 72–79
nonconservative forces
versus conservative
forces, 131–132
nonuniform acceleration, 37
nonuniform speed, 30
normal force
about, 358
friction, 86
north pole, magnetism, 288
numerical vectors, 47–49
Index 365• O •
objects in motion, 8–9
ohm, 358
Ohm’s law
about, 273–275
current flow, 273–274
resistivity, 274–275
oscillate, 358
• P •
p symbol, 139
parallel circuits
capacitors, 283–284
electrons, 276–278
parallel plate capacitors,
261–262
pascal, 358
pendulums, simple harmonic
motion, 203–204
period, 358
periodic motion
about, 189
elastic limit, 190
elasticity, 189–191
Hooke’s law, 189–191
ideal spring, 190
restoring force, 191
simple harmonic motion,
191–202
periodic simple harmonic
motion, 196–197
permanent magnets, 288
permittivity of free space,
255
phase changes, 216–218
photons, 351, 358
physics
about, 7–8
history, 7
math and, 14
physics theories
about, 349
absolute measures, 354
Big Bang, 353
black holes, 351
gravity curves space,
351–352
Heisenberg Uncertainty
Principle, 350–351
matter and antimatter
destroy each other, 352
measure smallest distance,
349–350
microwave ovens, 353–354
neutron star, 351
Planck, Max, 349–350
smallest time, 350
supernova explosions, 353
time as fourth dimension,
352
pivot point, torque, 161
Planck, Max, 349–350
plus-minus fad, 22
point charges
electric fields, 259–260
electric potential energy,
266–268
polarize, 358
positive acceleration, 35–36
positive charges, 258–259
potential energy,
about, 9, 358
converting into kinetic
energy, 130
gravity, 129–130
work, 128–130
power
about, 135, 358
alternate calculations, 136
units, 135–136
watts, 135–136
precision measurement,
21–22
pressure, 358
principle of conservation of
momentum, 143–148
problem-solving skills, 15
proton charges, 253–254
pushing and pulling currents,
magnetism, 295–298
pushing weight, work,
120–121
• Q •
quantitative size of magnetic
forces, 290–292
• R •
radians, 358
radiant heating, 225
radiation
about, 358
blackbodies, 226–227
light, 224–227
visibility, 225–226
rain, momentum, 142–143
ray diagrams, 328–331, 358
RC circuits
about, 359
electrons, 285–286
RCL circuits, 321–322
real image, 359
real values, 317–318
refracting light, 324–325
refraction, 359
resistance, 359
resistivity, Ohm’s law,
274–275
resistors, 359
restoring force, periodic
motion, 191
resultant, 359
resultant vectors, 45–46
reversible process, 248
root mean square, current
and voltage, 314–315
rotation, 153
rotational equilibrium,
166–171
rotational inertia, 359
rotational kinetic energy,
182–183
rotational motion
about, 173
angular momentum,
185–187
angular motion, 173–176
converting tangential
acceleration to angular
acceleration, 175
inertia, 175–182
kinetic energy, 180–185
from linear motion, 153–154
Newton’s second law,
173–176
rubber resistivity, 275
366 Physics For Dummies• S •
satellite orbits, angular
momentum, 186–187
satellite period, circular
motion, 112–113
scalar work, 120
scalars, 44–45, 359
scientific notation, 20
second law of motion, 66–72
second law of
thermodynamics
about, 246
Carnot engine, 248–250
heat engines, 246–248
series, 359
series circuits
capacitors, 284
electrons, 275–276
significant digits,
measurement, 21–22
silver thermal conductivity,
223
simple harmonic motion
about, 191, 359
acceleration, 198–200
angular frequency of mass
of spring, 200–202
elastic potential energy,
202–203
equilibrium point, 192–193
factoring energy into,
202–203
horizontal, 192–193
pendulums, 203–204
periodic, 196–197
sine wave, 194–196
velocity, 197–198
vertical, 192–193
sine wave, 194–196
slug, 66
smallest time physics theory,
350
Snell’s law, 324–325
solenoids, 302–303, 359
south pole, magnetism, 288
space travel aging, 343–344
special relativity, 359
specific heat capacities, 215,
245–246, 359
speed
about, 25, 29
acceleration, 40–41
average, 31
average versus uniform
motion, 31–32
displacement, 40–41
instantaneous, 30
light, 64, 326–327, 342,
346–347
measurement
displacement, 28–29
nonuniform, 30
uniform, 30
Spencer, Percy, 354
spherical aberration, 336
standard pressure, 359
Standard Temperature and
Pressure, 231
standard volume, 359
static electricity
about, 253
atoms, 253–254
electric fields, 258–262
electric forces, 254–257
electric potential energy,
262–270
electron charges, 253–254
parallel plate capacitors,
261–262
proton charges, 253–254
static friction, 87–89, 359
steel thermal conductivity,
223
styrofoam thermal
conductivity, 223
subtracting vectors, 46–47
subtraction, 22
sun’s mass, Theory of Special
Relativity, 346
supernova explosions
physics theory, 353
• T •
tangent, 24
tangential acceleration
about, 156
converting to angular
acceleration, 175
tangential motion
about, 154–156
acceleration, 156
centripetal, 156–158
test charges, electric fields,
259–260
Theory of Relativity, 11
Theory of Special Relativity
equivalence of matter and
energy, 345
inertial reference frame,
341–342
length contracts at high
speeds, 344–345
matter and antimatter,
345–346
Newton’s theories, 347–348
space travel, aging, 343–344
speed of light, 342, 346–347
sun’s mass, 346
time dilation, 343
thermal conductivity
about, 359
conduction, 222–223
materials, 223
thermal equilibrium, 235–236
thermal expansion, 359
thermals, 220
thermodynamics
about, 10, 207, 235, 359
absolute zero, 209–210
Celsius scale, 208–209
energy conservation,
236–246
Fahrenheit scale, 208–209
first law of
thermodynamics,
236–246
heat, 214–216
Kelvin system, 209–210
latent heat, 218
linear expansion, 210–213
phase changes, 216–218
second law of
thermodynamics,
246–250
thermal equilibrium,
235–236
third law of
thermodynamics, 250
Index 367thermodynamics (continued)
volume expansion, 213–214
zeroth law of
thermodynamics,
235–236
thin-lens equation, 335
thin lenses, 336
third law of motion
about, 72
angles, 75–77
equilibrium, 77–79
friction, 73–75
third law of thermodynamics,
250
time, 37–40
time as fourth dimension
physics theory, 352
time-averaged value, 317
time dilation theory, 343
torque
about, 160–161, 359
currents magnetism,
296–298
equation, 162
fulcrum, 161
generated, 164–165
inertia, 177–178, 179–182
lever arm, 162–164
moment of inertia, 162
pivot point, 161
vector, 165–166
torr, 231
total time, gravity, 95–96
triangles, 24
trigonometry, 23–24
turns, circular motion,
104–106
two dimensions, collisions,
151–152
• U •
Uncertainty Principle, 360
uniform acceleration, 37
uniform circular motion, 100
uniform magnetic field with
solenoids, 302–303
uniform motion versus
average speed, 31–32
uniform speed, 30
units
measurement, 15–16
power, 135–136
universal gas constant, 230
unmasking identities,
vectors, 53–57
uphill friction, 89–93
• V •
vectors
about, 43, 360
acceleration, 55–57
adding, 45–46
angles, 51–53
arrows, 44–45
components, 49–53
displacement, 54
equal, 45
gravity, 57–59
magnitudes, 43, 49–53
numerical, 47–49
resultant, 45–46
scalars, 44–45
subtracting, 46–47
torque, 165–166
unmasking identities, 53–57
velocity, 50, 54–55, 57–59
velocity
about, 360
circular motion, 106–108
mechanical energy, 134
momentum, 145–146
simple harmonic motion,
197–198
vectors, 50, 54–55, 57–59
vertical circular motion,
113–115
vertical simple harmonic
motion, 192–193
virtual image, 360
visibility, radiation, 225–226
volt, 360
voltage, 264–265
volume expansion, 213–214
• W •
water pressure, 232
wattage, 275
watts, 135–136
weight, 360
wood resistivity, 275
work
about, 119–120, 360
conservative force versus
nonconservative force,
131–132
drag, 121–122
kinetic energy, 123–128
measurement systems, 120
mechanical energy, 132–135
negative, 122–123
potential energy, 128–130
power, 135–136
pushing weight, 120–121
scalar, 120
• Z •
zeroth law of
thermodynamics,
235–236
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