Freshman Physics Forays

FRESHMAN PHYSICS FORAYS

by

John A. Cramer

Copyright 2019 by John A. Cramer

ISBN 978-0-463-17502-6

Smashwords Edition

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Table of Contents

Using These Forays

Basics

Foray 1. Units as Conventions

Foray 2. Aliens Numbers and Units #1

Foray 3. Aliens Numbers and Units #2

Foray 4. Vector Addition #1

Foray 5. Vector Addition #2

Foray 6. Vector Addition #3

Foray 7. Density and Hardness

Foray 8. Average vs. Instantaneous

Foray 9. Simulacra #1 Emission of Simulacra

Foray 10. Simulacra #2 Absorption of Similacra?

Foray 11. The Mathematics of Projectile Motion

Foray 12. The Mathematics of Uniform Circular Motion

Kinematics

Foray 13. Physical Quantities and Vectors

Foray 14. The Physics of Projectile Motion #1

Foray 15. The Physics of Projectile Motion #2

Foray 16. If the Moon should Fall on Us #1

Dynamics

Foray 17. Aristotle’s Law of Proportional Effects

Foray 18. Newton’s 2nd Law

Foray 19. The Kansas City Disaster

Foray 20. Steady as She Goes! Center of Mass and Stability

Foray 21. The Death Spiral

Foray 22. The Mysterious Sliding Rocks of Death Valley

Foray 23. Don’t Make Waves

Rotation

Foray 24. Slingshot Dragsters

Foray 25. Newton’s 2nd Law for Rotation

Foray 26. How Did Galileo Miss This #1?

Foray 27. When Rolling without Slipping Begins

Foray 28. Bicycle Stability #1

Foray 29. Bicycle Stability #2

Gravitation

Foray 30. Why believe in Heliocentrism?

Foray 31. How Did Galileo Miss This #2?

Foray 32.

Descartes’ Vortex Theory of Planetary Motion

Foray 33. If the Moon should Fall on Us #2

Foray 34. Planet Formation

Foray 35. Will the Moon Escape?

Vibrations, Oscillations and Waves

Foray 36. Oscillation Frequencies

Foray 37. Ship Stability #2

Foray 38. Surface Waves in Water #1

Foray 39. Surface Waves in Water #2

Foray 40. Miss Bright Limericks #1

Foray 41. Rotating Bullet Cohesion

Thermodynamics

Foray 42. Absolute Zero

Foray 43. Does Global Warming Raise Sea Level?

Foray 44. Simulacra #3 Their Thermodynamics

Foray 45. The Thermodynamics of Heaven & Hell

Foray 46. Liebensraum for Atoms?

Foray 47. Cooling Your Coffee

Foray 48. Perpetual Motion Machines

Foray 49. Counting Accessible States

Foray 50. What is the Heart?

Foray 51. Boiling an Ostrich Egg

Fluids

Foray 52. Does Nature Abhor a Vacuum?

Foray 53. Will the Arctic Ice Raise Sea Level as it Melts

Foray 54. Mass of Planetary Atmospheres

Foray 55. Can a Ship Squat?

Foray 56. Sailing into the Wind

Electricity

Foray 57. Electric Field in a Grid of Charges

Foray 58. Energy for the Taking?

Foray 59. Self-Energy Calculation

Foray 60. Gauss’ Law

Magnetism

Foray 61. Effluvia Magnetism

Foray 62. Eddy Current Brakes

Foray 63. Direction of a Magnetic Field

Foray 64. Atomic Stability on a Neutron Star

Optics

Foray 65. Corner Cube Reflector

Foray 66. Mirages

Foray 67. LED Laser Focusing

Foray 68. Chephalopod Eyes #1

Foray 69. Chephalopod Eyes #2

Relativity and Cosmology

Foray 70. Warp Speed #1

Foray 71. Miss Bright Limericks #2

Foray 72. Miss Bright Limericks #3

Foray 73. Warp Speed #2

Foray 74. Invisibility Cloaks

Foray 75. The Steady State Theory and Continuous Creation of Hydrogen

Using These Forays

This is a collection of ideas for teaching introductory physics and introductory calculus-based physics with class activities that I call forays. The dictionary defines a foray as a venture or initial attempt in some field and that describes quite accurately the purposes of these activities. Physics is most fundamentally a way of thinking. Usually the thinking is about the behavior of matter and energy so one may be tempted to define physics in terms of its usual subject matter but that is a mistake that will very likely lead to poor teaching. What little I understand of student struggles with the subject, after more than forty years of teaching it, is that learning how to think like a physicist is a much greater challenge than learning the subject matter. These forays, accordingly, rarely have any plug-in aspects. They require invention and imagination much more than knowledge of specific facts or laws.

Statements of the activities are grouped together in text boxes with answers below the textboxes. I have usually copied the text boxes for handing out in class without at the same time giving students the answers. Answers can always be given out later. Note the forays are grouped under broad subject areas to facilitate coordinating them with the order of topics in the course.

These forays vary in style. Some are calculations while others are problems that require experimental procedures be followed or even invented. Some combine theory and experiment. A few are activities that, though they might begin in class, will need group work outside of class to complete. The answers provided can help you to spot these. Long answer activities usually require more time to complete. The level of difficulty also varies. Again, the given answers provide clues to the level of difficulty. Consider using some of these forays as term projects.

I find that activity teaching works best with classes small enough to break up into teacher monitored groups of three or four although some of the activities here may need to be restricted to one apparatus rather more like a demonstration for the entire class. Solutions and answers provided can be doled out piece-wise to keep students engaged if they bog down in a foray.

John A. Cramer

Basics

Foray 1. Units as Conventions

Units used in measurements are conventions. That is, they are chosen by scientists for convenience and might be other than they are. The choice then necessarily includes a standard that defines the unit. The standard must be reproducible for anyone who needs it (or else convenience is lost).

Break the class into a number of small groups. Each group will decide on its own standard of length. The standard must be an actual object (e.g., the height of the smallest person in the group or the width of a particular book). The group will assign a name to the unit. Standards and names must be unique to the group so the groups will now report these