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College Physics

SENIOR CONTRIBUTING AUTHORS

I RINA L YUBLINSKAYA , CUNY C OLLEGE OF S TATEN I SLAND

G REGG W OLFE , A VONWORTH H IGH S CHOOL

D OUGLAS I NGRAM , T EXAS C HRISTIAN U NIVERSITY

L IZA P UJJI , M ANUKAU I NSTITUTE OF T ECHNOLOGY

S UDHI O BEROI , R AMAN R ESEARCH I NSTITUTE

N ATHAN C ZUBA , S ABIO A CADEMY

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ENHANCED TEXTBOOK PART 1 ISBN-10 1-938168-08-9

ENHANCED TEXTBOOK PART 1 ISBN-13 978-1-938168-08-6

ENHANCED TEXTBOOK PART 2 ISBN-10 1-938168-10-0

ENHANCED TEXTBOOK PART 2 ISBN-13 978-1-938168-10-9

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Table of Contents

Preface 1

1 Introduction: The Nature of Science and Physics 7

Physics: An Introduction 8

Physical Quantities and Units 15

Accuracy, Precision, and Significant Figures 22

Approximation 27

2 Kinematics 33

Displacement 34

Vectors, Scalars, and Coordinate Systems 37

Time, Velocity, and Speed 39

Acceleration 43

Motion Equations for Constant Acceleration in One Dimension 55

Problem-Solving Basics for One Dimensional Kinematics 66

Falling Objects 67

Graphical Analysis of One Dimensional Motion 75

3 Two-Dimensional Kinematics 97

Kinematics in Two Dimensions: An Introduction 98

Vector Addition and Subtraction: Graphical Methods 101

Vector Addition and Subtraction: Analytical Methods 109

Projectile Motion 115

Addition of Velocities 123

4 Dynamics: Force and Newton's Laws of Motion 143

Development of Force Concept 146

Newton's First Law of Motion: Inertia 147

Newton's Second Law of Motion: Concept of a System 148

Newton's Third Law of Motion: Symmetry in Forces 154

Normal, Tension, and Other Examples of Force 159

Problem-Solving Strategies 167

Further Applications of Newton's Laws of Motion 169

Extended Topic: The Four Basic Forces—An Introduction 176

5 Further Applications of Newton's Laws: Friction, Drag, and Elasticity 193

Friction 194

Drag Forces 200

Elasticity: Stress and Strain 205

6 Gravitation and Uniform Circular Motion 223

Rotation Angle and Angular Velocity 224

Centripetal Acceleration 228

Centripetal Force 232

Fictitious Forces and Non-inertial Frames: The Coriolis Force 236

Newton's Universal Law of Gravitation 239

Satellites and Kepler's Laws: An Argument for Simplicity 247

7 Work, Energy, and Energy Resources 265

Work: The Scientific Definition 266

Kinetic Energy and the Work-Energy Theorem 270

Gravitational Potential Energy 275

Conservative Forces and Potential Energy 281

Nonconservative Forces 285

Conservation of Energy 290

Power 294

Work, Energy, and Power in Humans 298

World Energy Use 301

8 Linear Momentum and Collisions 319

Linear Momentum and Force 320

Impulse 323

Conservation of Momentum 327

Elastic Collisions in One Dimension 332

Inelastic Collisions in One Dimension 335

Collisions of Point Masses in Two Dimensions 339

Introduction to Rocket Propulsion 344

9 Statics and Torque 361

The First Condition for Equilibrium 362

The Second Condition for Equilibrium 363

Stability 368

Applications of Statics, Including Problem-Solving Strategies 372

Simple Machines 375

Forces and Torques in Muscles and Joints 379

10 Rotational Motion and Angular Momentum 395

Angular Acceleration 397

Kinematics of Rotational Motion 401

Dynamics of Rotational Motion: Rotational Inertia 406

Rotational Kinetic Energy: Work and Energy Revisited 411

Angular Momentum and Its Conservation 418

Collisions of Extended Bodies in Two Dimensions 424

Gyroscopic Effects: Vector Aspects of Angular Momentum 429

11 Fluid Statics 445

What Is a Fluid? 446

Density 447

Pressure 449

Variation of Pressure with Depth in a Fluid 453

Pascal’s Principle 457

Gauge Pressure, Absolute Pressure, and Pressure Measurement 460

Archimedes’ Principle 464

Cohesion and Adhesion in Liquids: Surface Tension and Capillary Action 470

Pressures in the Body 479

12 Fluid Dynamics and Its Biological and Medical Applications 495

Flow Rate and Its Relation to Velocity 496

Bernoulli’s Equation 501

The Most General Applications of Bernoulli’s Equation 505

Viscosity and Laminar Flow; Poiseuille’s Law 509

The Onset of Turbulence 517

Motion of an Object in a Viscous Fluid 519

Molecular Transport Phenomena: Diffusion, Osmosis, and Related Processes 521

13 Temperature, Kinetic Theory, and the Gas Laws 535

Temperature 536

Thermal Expansion of Solids and Liquids 542

The Ideal Gas Law 549

Kinetic Theory: Atomic and Molecular Explanation of Pressure and Temperature 555

Phase Changes 562

Humidity, Evaporation, and Boiling 566

14 Heat and Heat Transfer Methods 583

Heat 584

Temperature Change and Heat Capacity 586

Phase Change and Latent Heat 592

Heat Transfer Methods 598

Conduction 599

Convection 605

Radiation 609

15 Thermodynamics 627

The First Law of Thermodynamics 628

The First Law of Thermodynamics and Some Simple Processes 634

Introduction to the Second Law of Thermodynamics: Heat Engines and Their Efficiency 642

Carnot’s Perfect Heat Engine: The Second Law of Thermodynamics Restated 647

Applications of Thermodynamics: Heat Pumps and Refrigerators 652

Entropy and the Second Law of Thermodynamics: Disorder and the Unavailability of Energy 657

Statistical Interpretation of Entropy and the Second Law of Thermodynamics: The Underlying Explanation 664

16 Oscillatory Motion and Waves 681

Hooke’s Law: Stress and Strain Revisited 683

Period and Frequency in Oscillations 687

Simple Harmonic Motion: A Special Periodic Motion 689

The Simple Pendulum 694

Energy and the Simple Harmonic Oscillator 696

Uniform Circular Motion and Simple Harmonic Motion 699

Damped Harmonic Motion 702

Forced Oscillations and Resonance 706

Waves 708

Superposition and Interference 711

Energy in Waves: Intensity 716

17 Physics of Hearing 731

Sound 732

Speed of Sound, Frequency, and Wavelength 734

Sound Intensity and Sound Level 739

Doppler Effect and Sonic Booms 744

Sound Interference and Resonance: Standing Waves in Air Columns 748

Hearing 757

Ultrasound 762

18 Electric Charge and Electric Field 781

Static Electricity and Charge: Conservation of Charge 784

Conductors and Insulators 789

Conductors and Electric Fields in Static Equilibrium 793

Coulomb’s Law 797

Electric Field: Concept of a Field Revisited 799

Electric Field Lines: Multiple Charges 802

Electric Forces in Biology 806

Applications of Electrostatics 808

19 Electric Potential and Electric Field 831

Electric Potential Energy: Potential Difference 833

Electric Potential in a Uniform Electric Field 840

Electrical Potential Due to a Point Charge 845

Equipotential Lines 847

Capacitors and Dielectrics 851

Capacitors in Series and Parallel 859

Energy Stored in Capacitors 863

20 Electric Current, Resistance, and Ohm's Law 877

Current 878

Ohm’s Law: Resistance and Simple Circuits 884

Resistance and Resistivity 887

Electric Power and Energy 893

Alternating Current versus Direct Current 896

Electric Hazards and the Human Body 900

Nerve Conduction–Electrocardiograms 905

21 Circuits, Bioelectricity, and DC Instruments 923

Resistors in Series and Parallel 924

Electromotive Force: Terminal Voltage 933

Kirchhoff’s Rules 942

DC Voltmeters and Ammeters 948

Null Measurements 952

DC Circuits Containing Resistors and Capacitors 955

22 Magnetism 975

Magnets 976

Ferromagnets and Electromagnets 979

Magnetic Fields and Magnetic Field Lines 983

Magnetic Field Strength: Force on a Moving Charge in a Magnetic Field 984

Force on a Moving Charge in a Magnetic Field: Examples and Applications 987

The Hall Effect 991

Magnetic Force on a Current-Carrying Conductor 994

Torque on a Current Loop: Motors and Meters 996

Magnetic Fields Produced by Currents: Ampere’s Law 999

Magnetic Force between Two Parallel Conductors 1004

More Applications of Magnetism 1006

23 Electromagnetic Induction, AC Circuits, and Electrical Technologies 1025

Induced Emf and Magnetic Flux 1026

Faraday’s Law of Induction: Lenz’s Law 1029

Motional Emf 1031

Eddy Currents and Magnetic Damping 1034

Electric Generators 1038

Back Emf 1041

Transformers 1042

Electrical Safety: Systems and Devices 1046

Inductance 1050

RL Circuits 1055

Reactance, Inductive and Capacitive 1056

RLC Series AC Circuits 1060

24 Electromagnetic Waves 1081

Maxwell’s Equations: Electromagnetic Waves Predicted and Observed 1083

Production of Electromagnetic Waves 1085

The Electromagnetic Spectrum 1089

Energy in Electromagnetic Waves 1102

25 Geometric Optics 1115

The Ray Aspect of Light 1116

The Law of Reflection 1117

The Law of Refraction 1120

Total Internal Reflection 1125

Dispersion: The Rainbow and Prisms 1131

Image Formation by Lenses 1136

Image Formation by Mirrors 1149

26 Vision and Optical Instruments 1167

Physics of the Eye 1168

Vision Correction 1172

Color and Color Vision 1176

Microscopes 1179

Telescopes 1185

Aberrations 1188

27 Wave Optics 1199

The Wave Aspect of Light: Interference 1200

Huygens's Principle: Diffraction 1202

Young’s Double Slit Experiment 1204

Multiple Slit Diffraction 1210

Single Slit Diffraction 1214

Limits of Resolution: The Rayleigh Criterion 1217

Thin Film Interference 1222

Polarization 1226

*Extended Topic* Microscopy Enhanced by the Wave Characteristics of Light 1235

28 Special Relativity 1251

Einstein’s Postulates 1252

Simultaneity And Time Dilation 1254

Length Contraction 1261

Relativistic Addition of Velocities 1265

Relativistic Momentum 1270

Relativistic Energy 1272

29 Introduction to Quantum Physics 1289

Quantization of Energy 1291

The Photoelectric Effect 1294

Photon Energies and the Electromagnetic Spectrum 1297

Photon Momentum 1304

The Particle-Wave Duality 1308

The Wave Nature of Matter 1309

Probability: The Heisenberg Uncertainty Principle 1313

The Particle-Wave Duality Reviewed 1318

30 Atomic Physics 1331

Discovery of the Atom 1332

Discovery of the Parts of the Atom: Electrons and Nuclei 1334

Bohr’s Theory of the Hydrogen Atom 1341

X Rays: Atomic Origins and Applications 1348

Applications of Atomic Excitations and De-Excitations 1353

The Wave Nature of Matter Causes Quantization 1361

Patterns in Spectra Reveal More Quantization 1364

Quantum Numbers and Rules 1366

The Pauli Exclusion Principle 1372

31 Radioactivity and Nuclear Physics 1391

Nuclear Radioactivity 1392

Radiation Detection and Detectors 1397

Substructure of the Nucleus 1399

Nuclear Decay and Conservation Laws 1404

Half-Life and Activity 1411

Binding Energy 1417

Tunneling 1421

32 Medical Applications of Nuclear Physics 1437

Medical Imaging and Diagnostics 1439

Biological Effects of Ionizing Radiation 1442

Therapeutic Uses of Ionizing Radiation 1449

Food Irradiation 1451

Fusion 1452

Fission 1458

Nuclear Weapons 1463

33 Particle Physics 1479

The Yukawa Particle and the Heisenberg Uncertainty Principle Revisited 1481

The Four Basic Forces 1483

Accelerators Create Matter from Energy 1485

Particles, Patterns, and Conservation Laws 1489

Quarks: Is That All There Is? 1494

GUTs: The Unification of Forces 1502

34 Frontiers of Physics 1517

Cosmology and Particle Physics 1517

General Relativity and Quantum Gravity 1525

Superstrings 1531

Dark Matter and Closure 1531

Complexity and Chaos 1535

High-Temperature Superconductors 1537

Some Questions We Know to Ask 1539

Appendix A: Atomic Masses 1549

Appendix B: Selected Radioactive Isotopes 1555

Appendix C: Useful Information 1559

Appendix D: Glossary of Key Symbols and Notation 1563

Index 1677

About OpenStax Resources

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About College Physics for AP® Courses

College Physics for AP ® Courses is designed to engage students in their exploration of physics and help them apply these

concepts to the Advanced Placement® test Because physics is integral to modern technology and other sciences, the book alsoincludes content that goes beyond the scope of the AP® course to further student understanding The AP® Connection in eachchapter directs students to the material they should focus on for the AP® exam, and what content — although interesting — isnot necessarily part of the AP® curriculum This book is Learning List-approved for AP® Physics courses

Coverage, Scope, and Alignment to the AP® Curriculum

The current AP® Physics curriculum framework outlines the two full-year physics courses AP® Physics 1: Algebra-Based and

AP® Physics 2: Algebra-Based These two courses replaced the one-year AP® Physics B course, which over the years had become a fast-paced survey of physics facts and formulas that did not provide in-depth conceptual understanding of major physics ideas and the connections between them

AP® Physics 1 and 2 courses focus on the big ideas typically included in the first and second semesters of an algebra-based, introductory college-level physics course, providing students with the essential knowledge and skills required to support future advanced course work in physics The AP® Physics 1 curriculum includes mechanics, mechanical waves, sound, and

electrostatics The AP® Physics 2 curriculum focuses on thermodynamics, fluid statics, dynamics, electromagnetism, geometric and physical optics, quantum physics, atomic physics, and nuclear physics Seven unifying themes of physics called the Big Ideas each include three to seven enduring understandings (EU), which are themselves composed of essential knowledge (EK) that provides details and context for students as they explore physics

AP® science practices emphasize inquiry-based learning and development of critical thinking and reasoning skills Inquiry usually

uses a series of steps to gain new knowledge, beginning with an observation and following with a hypothesis to explain theobservation; then experiments are conducted to test the hypothesis, gather results, and draw conclusions from data The AP®framework has identified seven major science practices, which can be described by short phrases: using representations andmodels to communicate information and solve problems; using mathematics appropriately; engaging in questioning; planningand implementing data collection strategies; analyzing and evaluating data; justifying scientific explanations; and connectingconcepts The framework’s Learning Objectives merge content (EU and EK) with one or more of the seven science practices thatstudents should develop as they prepare for the AP®Physics exam.

College Physics for AP ® Courses is based on the OpenStax College Physics text, adapted to focus on the AP curriculum's concepts and practices Each chapter of OpenStax College Physics for AP ® Courses begins with a Connection for AP ® Courses

introduction that explains how the content in the chapter sections align to the Big Ideas, enduring understandings, and essential

knowledge in the AP® framework This textbook contains a wealth of information, and the Connection for AP ® Coursessectionswill help you distill the required AP®content from material that, although interesting, exceeds the scope of an introductory-levelcourse

Each section opens with the program’s learning objectives as well as the AP®learning objectives and science practices

addressed We have also developed Real World Connections features and Applying the Science Practices features that highlight

concepts, examples, and practices in the framework

• 1 Introduction: The Nature of Science and Physics

• 2 Kinematics

• 3 Two-Dimensional Kinematics

• 4 Dynamics: Force and Newton's Laws of Motion

• 5 Further Applications of Newton's Laws: Friction, Drag, and Elasticity

• 6 Gravitation and Uniform Circular Motion

• 7 Work, Energy, and Energy Resources

• 8 Linear Momentum and Collisions

• 9 Statics and Torque

• 10 Rotational Motion and Angular Momentum

• 11 Fluid Statics

• 12 Fluid Dynamics and Its Biological and Medical Applications

• 13 Temperature, Kinetic Theory, and the Gas Laws

• 14 Heat and Heat Transfer Methods

• 15 Thermodynamics

• 16 Oscillatory Motion and Waves

• 17 Physics of Hearing

• 18 Electric Charge and Electric Field

• 19 Electric Potential and Electric Field

• 20 Electric Current, Resistance, and Ohm's Law

• 21 Circuits, Bioelectricity, and DC Instruments

• 31 Radioactivity and Nuclear Physics

• 32 Medical Applications of Nuclear Physics

• 33 Particle Physics

• 34 Frontiers of Physics

• Appendix A: Atomic Masses

• Appendix B: Selected Radioactive Isotopes

• Appendix C: Useful Information

• Appendix D: Glossary of Key Symbols and Notation

Pedagogical Foundation and Features

College Physics for AP ® Coursesis organized so that topics are introduced conceptually with a steady progression to precisedefinitions and analytical applications The analytical, problem-solving aspect is tied back to the conceptual before moving on toanother topic Each introductory chapter, for example, opens with an engaging photograph relevant to the subject of the chapterand interesting applications that are easy for most students to visualize

• Connections for AP ® Courses introduce each chapter and explain how its content addresses the AP®curriculum

• Worked Examples Examples start with problems based on real-life situations, then describe a strategy for solving the

problem that emphasizes key concepts The subsequent detailed mathematical solution also includes a follow-up

• Problem-solving Strategies are presented independently and subsequently appear at crucial points in the text where

students can benefit most from them

• Misconception Alerts address common misconceptions that students may bring to class.

• Take-Home Investigations provide the opportunity for students to apply or explore what they have learned with a

hands-on activity

• Real World Connections highlight important concepts and examples in the AP®framework

• Applying the Science Practices includes activities and challenging questions that engage students while they apply the

AP®science practices

• Things Great and Small explains macroscopic phenomena (such as air pressure) with submicroscopic phenomena (such

as atoms bouncing off of walls)

• PhET Explorations link students to interactive PHeT physics simulations, developed by the University of Colorado, to help

them further explore the physics concepts they have learned about in their book module

Assessment

College Physics for AP ® Coursesoffers a wealth of assessment options, including the following end-of-module problems:

• Integrated Concept Problems challenge students to apply both conceptual knowledge and skills to solve a problem.

• Unreasonable Results encourage students to solve a problem and then evaluate why the premise or answer to the

problem are unrealistic

• Construct Your Own Problem requires students to construct how to solve a particular problem, justify their starting

assumptions, show their steps to find the solution to the problem, and finally discuss the meaning of the result

• Test Prep for AP ® Courses includes assessment items with the format and rigor found in the AP®exam to help preparestudents for the exam

AP Physics Collection

College Physics for AP ® Coursesis a part of the AP Physics Collection The AP Physics Collection is a free, turnkey solution foryour AP®Physics course, brought to you through a collaboration between OpenStax and Rice Online Learning The integratedcollection pairs the OpenStax College Physics for AP®Courses text with Concept Trailer videos, instructional videos, problemsolution videos, and a correlation guide to help you align all of your content The instructional videos and problem solution videoswere developed by Rice Professor Jason Hafner and AP®Physics teachers Gigi Nevils-Noe and Matt Wilson through RiceOnline Learning You can access all of this free material through the College Physics for AP®Courses page on openstax.org

Additional Resources

Student and Instructor Resources

We’ve compiled additional resources for both students and instructors, including Getting Started Guides, an instructor solutionmanual, and instructional videos Instructor resources require a verified instructor account, which you can apply for when you log

in or create your account on openstax.org Take advantage of these resources to supplement your OpenStax book

Partner Resources

OpenStax Partners are our allies in the mission to make high-quality learning materials affordable and accessible to students andinstructors everywhere Their tools integrate seamlessly with our OpenStax titles at a low cost To access the partner resourcesfor your text, visit your book page on openstax.org

About the Authors

Senior Contributing Authors

Irina Lyublinskaya, CUNY College of Staten Island

Gregg Wolfe, Avonworth High School

Douglas Ingram, Trinity Christian University

Liza Pujji, Manukau Institute of Technology, New Zealand

Sudhi Oberoi, Visiting Research Student, QuIC Lab, Raman Research Institute, India

Nathan Czuba, Sabio Academy

Julie Kretchman, Science Writer, BS, University of Toronto

John Stoke, Science Writer, MS, University of Chicago

David Anderson, Science Writer, PhD, College of William and Mary

Erika Gasper, Science Writer, MA, University of California, Santa Cruz

Advanced Placement Teacher Reviewers

John Boehringer, Prosper High School

Victor Brazil, Petaluma High School

Michelle Burgess, Avon Lake High School

Bryan Callow, Lindenwold High School

Brian Hastings, Spring Grove Area School District

Alexander Lavy, Xavier High School

Jerome Mass, Glastonbury Public Schools

Faculty Reviewers

John Aiken, Georgia Institute of Technology

Robert Arts, University of Pikeville

Anand Batra, Howard University

Michael Ottinger, Missouri Western State University

James Smith, Caldwell University

Ulrich Zurcher, Cleveland State University

To the AP® Physics Student

The fundamental goal of physics is to discover and understand the “laws” that govern observed phenomena in the world around

us Why study physics? If you plan to become a physicist, the answer is obvious—introductory physics provides the foundation for your career; or if you want to become an engineer, physics provides the basis for the engineering principles used to solve applied and practical problems For example, after the discovery of the photoelectric effect by physicists, engineers developed photocells that are used in solar panels to convert sunlight to electricity What if you are an aspiring medical doctor? Although the applications of the laws of physics may not be obvious, their understanding is tremendously valuable Physics is involved in medical diagnostics, such as x-rays, magnetic resonance imaging (MRI), and ultrasonic blood flow measurements Medical therapy sometimes directly involves physics; cancer radiotherapy uses ionizing radiation What if you are planning a nonscience career? Learning physics provides you with a well-rounded education and the ability to make important decisions, such as evaluating the pros and cons of energy production sources or voting on decisions about nuclear waste disposal

This AP® Physics 1 course begins with kinematics, the study of motion without considering its causes Motion is everywhere:

from the vibration of atoms to the planetary revolutions around the Sun Understanding motion is key to understanding other

concepts in physics You will then study dynamics, which considers the forces that affect the motion of moving objects and

systems Newton’s laws of motion are the foundation of dynamics These laws provide an example of the breadth and simplicity

of the principles under which nature functions One of the most remarkable simplifications in physics is that only four distinct forces account for all known phenomena Your journey will continue as you learn about energy Energy plays an essential role both in everyday events and in scientific phenomena You can likely name many forms of energy, from that provided by our foods, to the energy we use to run our cars, to the sunlight that warms us on the beach The next stop is learning about

oscillatory motion and waves All oscillations involve force and energy: you push a child in a swing to get the motion started and you put energy into a guitar string when you pluck it Some oscillations create waves For example, a guitar creates sound waves You will conclude this first physics course with the study of static electricity and electric currents Many of the

characteristics of static electricity can be explored by rubbing things together Rubbing creates the spark you get from walking across a wool carpet, for example Similarly, lightning results from air movements under certain weather conditions

In the AP® Physics 2 course, you will continue your journey by studying fluid dynamics, which explains why rising smoke curls and twists and how the body regulates blood flow The next stop is thermodynamics, the study of heat transfer—energy in

transit—that can be used to do work Basic physical laws govern how heat transfers and its efficiency Then you will learn more

about electric phenomena as you delve into electromagnetism An electric current produces a magnetic field; similarly, a magnetic field produces a current This phenomenon, known as magnetic induction, is essential to our technological society

The generators in cars and nuclear plants use magnetism to generate a current Other devices that use magnetism to induce currents include pickup coils in electric guitars, transformers of every size, certain microphones, airport security gates, and

damping mechanisms on sensitive chemical balances From electromagnetism you will continue your journey to optics, the

study of light You already know that visible light is the type of electromagnetic waves to which our eyes respond Through vision, light can evoke deep emotions, such as when we view a magnificent sunset or glimpse a rainbow breaking through the clouds

Optics is concerned with the generation and propagation of light The quantum mechanics, atomic physics, and nuclear physics are at the end of your journey These areas of physics have been developed at the end of the 19th and early 20th

centuries and deal with submicroscopic objects Because these objects are smaller than we can observe directly with our senses and generally must be observed with the aid of instruments, parts of these physics areas may seem foreign and bizarre to you at first However, we have experimentally confirmed most of the ideas in these areas of physics

AP® Physics is a challenging course After all, you are taking physics at the introductory college level You will discover that some concepts are more difficult to understand than others; most students, for example, struggle to understand rotational motionand angular momentum or particle-wave duality The AP® curriculum promotes depth of understanding over breadth of content,

and to make your exploration of topics more manageable, concepts are organized around seven major themes called the Big Ideas that apply to all levels of physical systems and interactions between them (see web diagram below) Each Big Idea identifies enduring understandings (EU), essential knowledge (EK), and illustrative examples that support key concepts

and content Simple descriptions define the focus of each Big Idea

• Big Idea 1: Objects and systems have properties

• Big Idea 2: Fields explain interactions

• Big Idea 3: The interactions are described by forces

• Big Idea 4: Interactions result in changes

• Big Idea 5: Changes are constrained by conservation laws

• Big Idea 6: Waves can transfer energy and momentum

• Big Idea 7: The mathematics of probability can to describe the behavior of complex and quantum mechanical systems

Doing college work is not easy, but completion of AP® classes is a reliable predictor of college success and prepares you for subsequent courses The more you engage in the subject, the easier your journey through the curriculum will be Bring your enthusiasm to class every day along with your notebook, pencil, and calculator Prepare for class the day before, and reviewconcepts daily Form a peer study group and ask your teacher for extra help if necessary The AP® lab program focuses on more open-ended, student-directed, and inquiry-based lab investigations designed to make you think, ask questions, and analyze data like scientists You will develop critical thinking and reasoning skills and apply different means of communicating information Bythe time you sit for the AP® exam in May, you will be fluent in the language of physics; because you have been doing real science, you will be ready to show what you have learned Along the way, you will find the study of the world around us to be one

of the most relevant and enjoyable experiences of your high school career

Irina Lyublinskaya, PhD

Professor of Science Education

To the AP® Physics Teacher

The AP® curriculum was designed to allow instructors flexibility in their approach to teaching the physics courses College

Physics for AP ® Courses helps you orient students as they delve deeper into the world of physics Each chapter includes a

Connection for AP® Courses introduction that describes the AP® Physics Big Ideas, enduring understandings, and essential knowledge addressed in that chapter

Each section starts with specific AP® learning objectives and includes essential concepts, illustrative examples, and science practices, along with suggestions for applying the learning objectives through take-home experiments, virtual lab investigations,and activities and questions for preparation and review At the end of each section, students will find the Test Prep for AP® courses with multiple-choice and open-response questions addressing AP® learning objectives to help them prepare for the AP® exam

College Physics for AP ® Courses has been written to engage students in their exploration of physics and help them relate what

they learn in the classroom to their lives outside of it Physics underlies much of what is happening today in other sciences and intechnology Thus, the book content includes interesting facts and ideas that go beyond the scope of the AP® course The AP®Connection in each chapter directs students to the material they should focus on for the AP® exam, and what content—although interesting—is not part of the AP® curriculum Physics is a beautiful and fascinating science It is in your hands to engage andinspire your students to dive into an amazing world of physics, so they can enjoy it beyond just preparation for the AP® exam.Irina Lyublinskaya, PhD

Professor of Science Education

The concept map showing major links between Big Ideas and Enduring Understandings is provided below for visual reference.

1 INTRODUCTION: THE NATURE OF

SCIENCE AND PHYSICS

Figure 1.1Galaxies are as immense as atoms are small Yet the same laws of physics describe both, and all the rest of nature—an indication of the underlying unity in the universe The laws of physics are surprisingly few in number, implying an underlying simplicity to nature's apparent complexity (credit: NASA, JPL-Caltech, P Barmby, Harvard-Smithsonian Center for Astrophysics)

Chapter Outline

1.1 Physics: An Introduction 1.2 Physical Quantities and Units 1.3 Accuracy, Precision, and Significant Figures 1.4 Approximation

Connection for AP® Courses

What is your first reaction when you hear the word “physics”? Did you imagine working through difficult equations or memorizingformulas that seem to have no real use in life outside the physics classroom? Many people come to the subject of physics with abit of fear But as you begin your exploration of this broad-ranging subject, you may soon come to realize that physics plays amuch larger role in your life than you first thought, no matter your life goals or career choice

For example, take a look at the image above This image is of the Andromeda Galaxy, which contains billions of individual stars,huge clouds of gas, and dust Two smaller galaxies are also visible as bright blue spots in the background At a staggering 2.5million light years from Earth, this galaxy is the nearest one to our own galaxy (which is called the Milky Way) The stars andplanets that make up Andromeda might seem to be the furthest thing from most people's regular, everyday lives But Andromeda

is a great starting point to think about the forces that hold together the universe The forces that cause Andromeda to act as itdoes are the same forces we contend with here on Earth, whether we are planning to send a rocket into space or simply raisethe walls for a new home The same gravity that causes the stars of Andromeda to rotate and revolve also causes water to flowover hydroelectric dams here on Earth Tonight, take a moment to look up at the stars The forces out there are the same as theones here on Earth Through a study of physics, you may gain a greater understanding of the interconnectedness of everything

we can see and know in this universe

Think now about all of the technological devices that you use on a regular basis Computers, smart phones, GPS systems, MP3players, and satellite radio might come to mind Next, think about the most exciting modern technologies that you have heardabout in the news, such as trains that levitate above tracks, “invisibility cloaks” that bend light around them, and microscopicrobots that fight cancer cells in our bodies All of these groundbreaking advancements, commonplace or unbelievable, rely on theprinciples of physics Aside from playing a significant role in technology, professionals such as engineers, pilots, physicians,physical therapists, electricians, and computer programmers apply physics concepts in their daily work For example, a pilot mustunderstand how wind forces affect a flight path and a physical therapist must understand how the muscles in the body

experience forces as they move and bend As you will learn in this text, physics principles are propelling new, exciting

technologies, and these principles are applied in a wide range of careers

In this text, you will begin to explore the history of the formal study of physics, beginning with natural philosophy and the ancientGreeks, and leading up through a review of Sir Isaac Newton and the laws of physics that bear his name You will also beintroduced to the standards scientists use when they study physical quantities and the interrelated system of measurementsmost of the scientific community uses to communicate in a single mathematical language Finally, you will study the limits of ourability to be accurate and precise, and the reasons scientists go to painstaking lengths to be as clear as possible regarding theirown limitations

Chapter 1 introduces many fundamental skills and understandings needed for success with the AP® Learning Objectives Whilethis chapter does not directly address any Big Ideas, its content will allow for a more meaningful understanding when these BigIdeas are addressed in future chapters For instance, the discussion of models, theories, and laws will assist you in

understanding the concept of fields as addressed in Big Idea 2, and the section titled ‘The Evolution of Natural Philosophy intoModern Physics' will help prepare you for the statistical topics addressed in Big Idea 7

This chapter will also prepare you to understand the Science Practices In explicitly addressing the role of models in representingand communicating scientific phenomena, Section 1.1 supports Science Practice 1 Additionally, anecdotes about historicalinvestigations and the inset on the scientific method will help you to engage in the scientific questioning referenced in SciencePractice 3 The appropriate use of mathematics, as called for in Science Practice 2, is a major focus throughout sections 1.2, 1.3,and 1.4

1.1 Physics: An Introduction

Figure 1.2The flight formations of migratory birds such as Canada geese are governed by the laws of physics (credit: David Merrett)

Learning Objectives

By the end of this section, you will be able to:

• Explain the difference between a principle and a law

• Explain the difference between a model and a theory

The physical universe is enormously complex in its detail Every day, each of us observes a great variety of objects and

phenomena Over the centuries, the curiosity of the human race has led us collectively to explore and catalog a tremendouswealth of information From the flight of birds to the colors of flowers, from lightning to gravity, from quarks to clusters of galaxies,from the flow of time to the mystery of the creation of the universe, we have asked questions and assembled huge arrays offacts In the face of all these details, we have discovered that a surprisingly small and unified set of physical laws can explainwhat we observe As humans, we make generalizations and seek order We have found that nature is remarkably cooperative—it

exhibits the underlying order and simplicity we so value.

It is the underlying order of nature that makes science in general, and physics in particular, so enjoyable to study For example,what do a bag of chips and a car battery have in common? Both contain energy that can be converted to other forms The law ofconservation of energy (which says that energy can change form but is never lost) ties together such topics as food calories,batteries, heat, light, and watch springs Understanding this law makes it easier to learn about the various forms energy takesand how they relate to one another Apparently unrelated topics are connected through broadly applicable physical laws,permitting an understanding beyond just the memorization of lists of facts

The unifying aspect of physical laws and the basic simplicity of nature form the underlying themes of this text In learning to applythese laws, you will, of course, study the most important topics in physics More importantly, you will gain analytical abilities thatwill enable you to apply these laws far beyond the scope of what can be included in a single book These analytical skills will helpyou to excel academically, and they will also help you to think critically in any professional career you choose to pursue Thismodule discusses the realm of physics (to define what physics is), some applications of physics (to illustrate its relevance toother disciplines), and more precisely what constitutes a physical law (to illuminate the importance of experimentation to theory)

Science and the Realm of Physics

Science consists of the theories and laws that are the general truths of nature as well as the body of knowledge they encompass.Scientists are continually trying to expand this body of knowledge and to perfect the expression of the laws that describe it

Physics is concerned with describing the interactions of energy, matter, space, and time, and it is especially interested in what

fundamental mechanisms underlie every phenomenon The concern for describing the basic phenomena in nature essentially

defines the realm of physics.

Physics aims to describe the function of everything around us, from the movement of tiny charged particles to the motion ofpeople, cars, and spaceships In fact, almost everything around you can be described quite accurately by the laws of physics.Consider a smart phone (Figure 1.3) Physics describes how electricity interacts with the various circuits inside the device This

knowledge helps engineers select the appropriate materials and circuit layout when building the smart phone Next, consider aGPS system Physics describes the relationship between the speed of an object, the distance over which it travels, and the time

it takes to travel that distance When you use a GPS device in a vehicle, it utilizes these physics equations to determine thetravel time from one location to another

Figure 1.3The Apple “iPhone” is a common smart phone with a GPS function Physics describes the way that electricity flows through the circuits of this device Engineers use their knowledge of physics to construct an iPhone with features that consumers will enjoy One specific feature of an iPhone

is the GPS function GPS uses physics equations to determine the driving time between two locations on a map (credit: @gletham GIS, Social, Mobile Tech Images)

Applications of Physics

You need not be a scientist to use physics On the contrary, knowledge of physics is useful in everyday situations as well as innonscientific professions It can help you understand how microwave ovens work, why metals should not be put into them, andwhy they might affect pacemakers (SeeFigure 1.4andFigure 1.5.) Physics allows you to understand the hazards of radiationand rationally evaluate these hazards more easily Physics also explains the reason why a black car radiator helps remove heat

in a car engine, and it explains why a white roof helps keep the inside of a house cool Similarly, the operation of a car's ignitionsystem as well as the transmission of electrical signals through our body's nervous system are much easier to understand whenyou think about them in terms of basic physics

Physics is the foundation of many important disciplines and contributes directly to others Chemistry, for example—since it dealswith the interactions of atoms and molecules—is rooted in atomic and molecular physics Most branches of engineering areapplied physics In architecture, physics is at the heart of structural stability, and is involved in the acoustics, heating, lighting,and cooling of buildings Parts of geology rely heavily on physics, such as radioactive dating of rocks, earthquake analysis, andheat transfer in the Earth Some disciplines, such as biophysics and geophysics, are hybrids of physics and other disciplines.Physics has many applications in the biological sciences On the microscopic level, it helps describe the properties of cell wallsand cell membranes (Figure 1.6andFigure 1.7) On the macroscopic level, it can explain the heat, work, and power associatedwith the human body Physics is involved in medical diagnostics, such as x-rays, magnetic resonance imaging (MRI), andultrasonic blood flow measurements Medical therapy sometimes directly involves physics; for example, cancer radiotherapyuses ionizing radiation Physics can also explain sensory phenomena, such as how musical instruments make sound, how theeye detects color, and how lasers can transmit information

It is not necessary to formally study all applications of physics What is most useful is knowledge of the basic laws of physics and

a skill in the analytical methods for applying them The study of physics also can improve your problem-solving skills

Furthermore, physics has retained the most basic aspects of science, so it is used by all of the sciences, and the study ofphysics makes other sciences easier to understand

Figure 1.4The laws of physics help us understand how common appliances work For example, the laws of physics can help explain how microwave ovens heat up food, and they also help us understand why it is dangerous to place metal objects in a microwave oven (credit: MoneyBlogNewz)

Figure 1.5These two applications of physics have more in common than meets the eye Microwave ovens use electromagnetic waves to heat food Magnetic resonance imaging (MRI) also uses electromagnetic waves to yield an image of the brain, from which the exact location of tumors can be determined (credit: Rashmi Chawla, Daniel Smith, and Paul E Marik)

Figure 1.6Physics, chemistry, and biology help describe the properties of cell walls in plant cells, such as the onion cells seen here (credit: Umberto Salvagnin)

Figure 1.7An artist's rendition of the the structure of a cell membrane Membranes form the boundaries of animal cells and are complex in structure and function Many of the most fundamental properties of life, such as the firing of nerve cells, are related to membranes The disciplines of biology, chemistry, and physics all help us understand the membranes of animal cells (credit: Mariana Ruiz)

Models, Theories, and Laws; The Role of Experimentation

The laws of nature are concise descriptions of the universe around us; they are human statements of the underlying laws or rulesthat all natural processes follow Such laws are intrinsic to the universe; humans did not create them and so cannot changethem We can only discover and understand them Their discovery is a very human endeavor, with all the elements of mystery,imagination, struggle, triumph, and disappointment inherent in any creative effort (SeeFigure 1.8andFigure 1.9.) The

cornerstone of discovering natural laws is observation; science must describe the universe as it is, not as we may imagine it tobe