CP02_SE_LAB_ FM 3/5/01 12:28 PM Page i CONCEPTUAL PHYSICS Laboratory Manual Paul Robinson San Mateo High School San Mateo, California Illustrated by Paul G. Hewitt Needham, Massachusetts Upper Saddle River, New Jersey Glenview, Illinois CP02_SE_LAB_ FM 6/20/08 9:24 AM Page ii Contributors Consultants Roy Unruh Kenneth Ford University of Northern Iowa Germantown Academy Cedar Falls, Iowa Fort Washington, Pennsylvania Tim Cooney Jay Obernolte Price Laboratory School University of California Cedar Falls, Iowa Los Angeles, California Clarence Bakken Gunn High School Palo Alto, California Cover photograph: Motor Press Agent/Superstock, Inc. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. When such a designation appears in this book and the publisher was aware of a trademark claim, the designa- tion has been printed in initial capital letters (e.g., Macintosh). Copyright © 2002 by Prentice-Hall, Inc., Upper Saddle River, New Jersey 07458. All rights reserved. Printed in the United States of America. This pub- lication is protected by copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval sys- tem, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permis- sion(s), write to: Rights and Permissions Department. ISBN 0-13-054257-1 22 V 031 13 12 11 ii CP02_SE_LAB_ FM 3/5/01 12:28 PM Page iii Acknowledgments Most of the ideas in this manual come from teachers who share their ideas at American Association of Physics Teachers (AAPT) meetings that I have attended since my first year of teaching. This sharing of ideas and coopera- tive spirit is a hallmark of our profession. Many more individuals have contributed their ideas and insights freely and openly than I can mention here. The greatest contributors are Roy Unruh and Tim Cooney, principal authors of the PRISMS (Physics Resources and Instructional Strategies for Motivating Students) Guide. I am especially thankful to them and others on the PRISMS team: Dan McGrail, Ken Shafer, Bob Wilson, Peggy Steffen, and Rollie Freel. For contributions and feedback to the first edition, I am grateful to Brad Huff, Bill von Felten, Manuel Da Costa, and Clarence Bakken, as well as the students of Edison Computech High School who provided valuable feedback. I am especially indebted to my talented former student Jay Obernolte, who developed computer soft- ware that originally accompanied this manual. For helpful lab ideas I thank Evan Jones, Sierra College; Dave Wall, City College of San Francisco; David Ewing, Southwestern Georgia University; and Sheila Cronin, Avon High School, CT, for her adaptations of CASTLE curriculum. Thanks go to Paul Tipler; Frank Crawford, UC Berkeley; Verne Rockcastle, Cornell University; and the late Lester Hirsch for their inspira- tion. I am especially grateful to Ken Ford, who critiqued this third edition and to my talented and spirited students at San Mateo High School who constantly challenge and inspire me. For suggestions on integrating the computer in the physics laboratory, I am grateful to my AAPT colleagues Dewey Dykstra, Robert H. Good, Charles Hunt, and Dave and Christine Vernier. Thanks also to Dave Griffith, Kevin Mather, and Paul Stokstad of PASCO Scientific for their professional assistance. I am grateful to my computer consultant and long time friend Skip Wagner for his creative expertise on the computer. For production assistance I thank Lisa Kappler Robinson and Helen Yan for hand-lettering all the illustrations. Love and thanks to my parents for their encouragement and support, and to my children—David, Kristen, and Brian—and my dear Ellyn—for being so patient and understanding! Most of all, I would like to express my gratitude to Paul Hewitt for his illustrations and many helpful suggestions. Paul Robinson iii CP02_SE_LAB_ FM 3/5/01 12:28 PM Page iv Contents To the Student x Goals, Graphing, Use of the Computer, Lab Reports, Safety in the Physics Laboratory, Emergency Procedures The laboratory activities and experiments are listed here with the lab topic in italics and the purpose of each lab is stated under the title of the lab. 1 Making Hypotheses – Inquiry Method 1 To practice using observations to make hypotheses. 2 The Physics 500 – Measuring Speed 3 To compute the average speed of at least three different races and to participate in at least one race. 3 The Domino Effect – Maximizing Average Speed 5 To investigate the ways in which distance, time, and average speed are interrelated by maximizing the speed of falling dominoes. To become familiar with elementary graphing techniques. 4 Merrily We Roll Along! – Acceleration Down an Incline 9 To investigate the relationship between distance and time for a ball rolling down an incline. 5 Conceptual Graphing – Graphical Analysis of Motion 17 To make qualitative interpretations of motion from graphs. 6 Race Track – Acceleration 23 To introduce the concept of constantly changing speed. 7 Bull’s Eye – Projectile Motion 25 To investigate the independence of horizontal and vertical components of motion. To predict the landing point of a projectile. 8 Going Nuts – Inertia 29 To explore the concept of inertia. 9 Buckle Up! – Inertia 31 To demonstrate how Newton’s first law of motion is involved in collisions. 10 24-Hour Towing Service – Statics and Vectors 33 To find a technique to move a car when its wheels are locked. 11 Getting Pushy – Variables Affecting Acceleration 35 To investigate the relationship among mass, force, and acceleration. 12 Constant Force and Changing Mass – Mass and Acceleration 39 To investigate the relationship of mass on an accelerating system. 13 Constant Mass and Changing Force – Force and Acceleration 43 To investigate how increasing the applied force affects the acceleration of a system. iv CP02_SE_LAB_ FM 3/5/01 12:28 PM Page v 14 Impact Speed – Effect of Air Friction on Falling Bodies 47 To estimate the speed of a falling object as it strikes the ground. 15 Riding with the Wind – Components of Force 51 To investigate the relationships between the components of the force that propels a sailboat. 16 Balloon Rockets – Action and Reaction 55 To investigate action-reaction relationships. 17 Tension – Action and Reaction 57 To introduce the concept of tension in a string. 18 Tug-of-War – Action and Reaction 61 To investigate the tension in a string, the function of a simple pulley, and a simple “tug-of-war.” 19 Go Cart – Two-Body Collisions 65 To investigate the momentum imparted during elastic and inelastic collisions. 20 Tailgated by a Dart – Momentum Conservation 69 To estimate the speed of an object by applying conservation of momentum to an inelastic collision. 21 Making the Grade – Mechanical Energy 73 To investigate the force and the distance involved in moving an object up an incline. 22 Muscle Up! – Power 75 To determine the power that can be produced by various muscles of the human body. 23 Cut Short – Conservation of Energy 77 To illustrate the principle of conservation of energy with a pendulum. 24 Conserving Your Energy – Conservation of Energy 79 To measure the potential and kinetic energies of a pendulum in order to see whether energy is conserved. 25 How Hot Are Your Hot Wheels? – Efficiency 83 To measure the efficiency of a toy car on an inclined track. 26 Wrap Your Energy in a Bow – Energy and Work 85 To determine the energy transferred into an archer’s bow as the string is pulled back. 27 On a Roll – Friction and Energy 89 To investigate the relationship between the stopping distance and height from which a ball rolls down an incline. 28 Releasing Your Potential – Conservation of Energy 93 To find quantitative relationships among height, speed, mass, kinetic energy, and potential energy. 29 Slip-Stick – Coefficients of Friction 97 To investigate three types of friction and to measure the coefficient of friction for each type. 30 Going in Circles – Centripetal Acceleration 103 To determine the acceleration of an object at different positions on a rotating turntable. 31 Where’s Your CG? – Center of Gravity 107 To locate your center of gravity. Contents v CP02_SE_LAB_ FM 3/5/01 12:28 PM Page vi 32 Torque Feeler – Torque 111 To illustrate the qualitative differences between torque and force. 33 Weighing an Elephant – Balanced Torques 113 To determine the relationship between masses and distances from the fulcrum for a balanced see-saw. 34 Keeping in Balance – Balanced Torques 117 To use the principles of balanced torques to find the value of an unknown mass. 35 Rotational Derby – Rotational Inertia 121 To observe how objects of various shapes and masses roll down an incline and how their rotational inertias affect their rate of rotation. 36 Acceleration of Free Fall – Acceleration of Gravity 125 To measure the acceleration of an object during free fall with the help of a pendulum. 37 Computerized Gravity – Acceleration of Gravity 129 To measure the acceleration due to gravity, using the Laboratory Interfacing Disk. 38 Apparent Weightlessness – Free Fall 133 To observe the effects of gravity on objects in free fall. 39 Getting Eccentric – Elliptical Orbits 135 To get a feeling of the shapes of ellipses and the locations of their foci by drawing a few. 40 Trial and Error – Kepler’s Third Law 137 To discover Kepler’s third law of planetary motion through a procedure of trial and error using the computer. 41 Flat as a Pancake – Diameter of a BB 139 To estimate the diameter of a BB. 42 Extra Small – The Size of a Molecule 141 To estimate the size of a molecule of oleic acid. 43 Stretch – Elasticity and Hooke’s Law 143 To verify Hooke’s law and determine the spring constants for a spring and a rubber band.