2: Interactions

Activities & Reader (ISBN 0-7872-3929-1, 224 pages)

How to Use this Book    xi

Acknowledgments    xiii

Activities

  • 36 - Introducing Vectors    137
  • 37 - Representing Vectors Using Components    145
  • 38 - Changing Vector Representations    149
  • 39 - Adding Vectors    155
  • 40 - Finding Changes in Vector Quantities    161
  • 41 - Recognizing Interactions    165
  • 42 - Identifying Interactions    169
  • 43 - Interpreting Measurements of Forces    173
  • 44 - More Interpreting Measurements of Forces    179
  • 45 - Recognizing Forces in Realistic Situations    185
  • 46 - Comparing Magnitudes of Forces    191
  • 47 - More Comparing Magnitudes of Forces    195
  • 48 - Understanding Friction Forces    199
  • 49 - Calculating Forces Using Empirical Laws    205
  • 50 - Recognizing and Interpreting Free-Body Diagrams    209
  • 51 - Drawing and Using Free-Body Diagrams    215
  • 52 - Analyzing Physical Situations Using Free-Body Diagrams    223
  • 53 - Describing Physical Situations Using Free-Body Diagrams    227
  • 54 - Summarizing and Structuring Interactions    233
  • 55 - Analyzing Physical Situations Using Newton's First and Second Laws    235
  • 56 - More Analyzing Physical Situations Using Newton's First and Second Laws    243
  • 57 - Relating the Forces Exerted on an Object to its Motion    247
  • 58 - Making Distinctions Between Newton's Second and Third Laws    251
  • 59 - Reasoning with Newton's Laws    257
  • 60 - More Reasoning with Newton's Laws    261
  • 61 - Using Newton's Laws to Determine the Magnitudes and Directions of Forces    267
  • 62 - Solving Problems with Newton's Laws    273
  • 63 - Analyzing Forces without Empirical Laws    277
  • 64 - Calculating the Values of Physical Parameters and Quantities    281
  • 65 - Labeling Parts of Solutions and Executing Solution Plans    285
  • 66 - Developing Solution Plans and Solving Force Problems    293
  • 67 - Solving Force Problems: Reflection and Integration    297
  • 68 - Summarizing and Structuring Dynamics    301
  • 69 - Going Beyond Newton's Laws    303
  • 70 - Looking for New Principles    307

Reader: Chapter 2 — Describing Interactions

  • 2.0 Introduction    R37
    • What is meant by dynamics?    R37
    • Why is acceleration such an important concept?    R37
  • 2.1 INTERACTIONS AND FORCES    R37-46
    • Interactions    R37
      • how to tell when two objects are interacting    R37
      • What if the effect is not visible?    R37
    • Forces    R37,38
      • relationship between interactions and forces    R37
      • many different ways to say that two objects are interacting    R38
      • how a force might change during a time interval    R38
    • Measuring forces    R38
      • explaining why springs are preferred for measuring forces    R38
      • importance of knowing what a scale is actually measuring    R38
    • Units of force    R38
      • introducing the pound (lb) and the newton (N)    R38
      • converting from one unit of force to another    R38
    • Identifying forces    R39-41
      • identifying the objects interacting    R39
      • identifying the type of interaction    R39,40
      • determining the direction of a force    R40,41
    • Empirical force laws    R41,42
      • What is meant by an empirical force law?    R41
      • features common to all empirical laws    R41
      • Table I: Summary of the empirical laws for common forces    R42
      • role of magnitude vs. direction in the empirical laws    R42
    • Fundamental laws for forces vs. empirical laws    R42,43
      • What is meant by a fundamental force law?    R42
      • the process of determining empirical force laws    R42,43
      • limitations of empirical laws    R43
    • Fundamental laws for forces    R43
      • the fundamental forces covered in this course    R43
      • Table II: Summary of the fundamental laws for two common forces    R43
    • Free-body diagrams: A way to help us inventory forces    R44,45
      • the thinking behind a free-body diagram    R44
      • some valid free-body diagrams    R44
      • features of a free-body diagram    R44,45
      • optional features of a free-body diagram    R45
      • guidelines for drawing a free-body diagram    R45
    • The net force    R46
      • definition of net force    R46
  • 2.2 NEWTON'S LAWS OF MOTION    R47-52
    • Mass vs. weight    R47,48
      • definition of weight    R47
      • how to measure the weight of something    R47
      • definition of mass    R47
      • how to measure the mass of something    R47
      • comparing the mass and the weight on the earth versus on the moon    R47,48
      • gravitational mass versus inertial mass    R48
    • Newton's three laws of motion    R48-50
      • Newton's first law of motion    R48
        • verbal statement of Newton's 1st law    R48
        • definition of net force    R48
      • Newton's second law of motion    R49
        • verbal statement of Newton's 1st law    R49
        • mathematical statement of Newton's 1st law    R49
        • definitions of inertial mass and gravitational mass    R49
        • definition of equilibrium    R49
      • Newton's third law of motion    R50
        • verbal statement of Newton's 3rd law    R50
        • mathematical statement of Newton's 3rd law    R50
        • relationship between forces and interactions    R50
        • explanation of the terms action and reaction    R50
        • difference between a reaction force and a balancing force    R50
    • Newton's laws and reference frames    R50,51
      • confirming Newton's laws using a constant-velocity frame    R50
      • contradicting Newton's laws using an accelerating frame    R50
      • definition of inertial frame    R51
    • Newton's laws and free-body diagrams    R51,52
      • Newton's 2nd law in component form    R51
      • applying the definition of the net force using components    R52
  • 2.3 DYNAMICS    R52-60
    • An agenda for dynamics    R52,53
    • Kinematics versus dynamics    R53
    • Reasoning with Newton's laws    R53-56
      • equilibrium situations (net force is zero)    R54,55
      • non-equilibrium situations (net force is not zero)    R56
    • Solving problems with Newton's laws    R56-59
      • goal of this approach to learning physics    R56
      • importance of analysis and reasoning skills    R56
      • role of analysis and reasoning while problem solving    R56-58
      • overview of problem solving in physics    R59
      • diagrammatic representation of the problem-solving process    R59
      • meaning of the diagrammatic representation    R59
    • Summary    R59
    • Limitations of dynamics    R59,60
      • conditions needed to solve dynamics problems    R59
      • some situations in which the motion cannot be determined using dynamics alone    R60
    • Conclusion    R60

Appendix: Table of Common Forces

  • Contact Forces    A1-4
    • Normal force    A1
    • Tension force    A1
    • Spring force (also called Elastic force)    A2
    • Buoyant force    A2
    • Friction forces    A3
      • kinetic    A3
      • static    A3
    • Air resistance force (also called Drag force)    A4
  • Action-at-a-distance Forces    A5,6
    • Gravitational force    A5
      • near the surface of the Earth    A5
      • Universal Law of Gravitation    A5
    • Electrostatic force    A6
    • Magnetic force    A6