Newton’s First Law of Motion—Inertia

Aristotle on Motion

                     Aristotle 

            Copernicus and the Moving Earth

            Galileo and the Leaning Tower

                     Galileo Galilei  

            Galileo’s Inclined Planes

            Newton’s First Law of Motion

            Net Force

                     Isaac Newton  

                     Personal Essay  

            The Equilibrium Rule

            Support Force

            Equilibrium of Moving Things

            The Moving Earth

Whereas the study of mechanics in previous editions began with kinematics, we begin our study with forces—much easier to grasp for students. We postpone what I call the black hole of physics instruction—overemphasis on kinematics. It is hoped that getting the course off with forces first will lessen the initial roadblock that kinematics poses. Of particular interest to me is the Personal Essay in the chapter, which relates to events that inspired me to pursue a life in physics—my meeting with Burl Grey on the sign-painting stages of Miami, Florida. Relative tensions in supporting cables is what first caught my interest in physics, and I hope to instill the same interest with your students with this opening chapter. It begins with a historical perspective, so if you're a history buff, you may want to expand on this.

Note that in introducing force I first use pounds—most familiar to your students. A quick transition, without fanfare, introduces the newton. I don’t make units a big deal and don’t get into the laborious task of unit conversions, which is more appropriate for physics majors.

The distinction between mass and weight will await the following chapter, when it’s needed in Newton’s second law. I see the key to good instruction as treating somewhat difficult topics only when they are used. For example, I see as pedagogical folly spending the first week on unit conversions, vector notation, graphical analysis, and scientific notation. How much better if the first week is a hook to promote class interest, with these things introduced later when needed.

A brief treatment of units and systems of measurement is provided in Appendix A. When representing magnitudes of quantities, consider the exaggerated symbol technique shown several places in the text.

There is 1 OHT (overhead transparency) for this chapter, 3 sketches of sign painters on a scaffold.

In the Practicing Physics book:

• Static Equilibrium

• The Equilibrium Rule: SF = 0

• Vectors and Equilibrium

In the Next-Time Questions book:

• Ball Swing                                                                      

• Pellet in the Spiral

• Falling Elephant and Feather