To most students today the mechanical equivalent of heat, called the Mayer-Joule principle, is simply a way to convert from calories to joules and vice versa. However, in linking work and heat--once thought to be disjointed concepts--it goes far beyond unit conversion. Heat had eluded understanding for two centuries after Galileo Galilei…

It's both surprising and rewarding when an old, standard problem reveals a subtlety that expands its pedagogic value. I realized recently that the role of gravity in the range equation for a projectile is not so simple as first appears. This realization may be completely obvious to others but was quite new to me.

A problem addressed infrequently in beginning physics courses is that of a moving body with changing mass. Elementary texts often have footnotes referring to jet planes and rockets but rarely do they go further. This omission is understandable because calculations with variable mass generally require the tools of calculus. This paper presents a…

A question we posed in a recent final examination has uncovered a fundamental difficulty for students in understanding destructive interference. The problem stated that glass of index n[subscript 3] was coated with a thin film of a substance with index n[subscript 2]. The question then asked the student to calculate (a) the minimum coating…

Presents the physical assumptions and mathematical expressions necessary to derive a fourth-order differential equation that describes the vibration of a particular car antenna. Contends that while students may not be able to derive or use the equation, they should be able to appreciate a guided derivation as an example of how physics is done.…

Presents an elementary physics problem, the solution of which illuminates physical meaning and its relation to real, imaginary, and complex mathematical quantities. (JRH)

Attempts to connect the seemingly disjointed points of view of diffraction and reflection. Light is reflected off of a metal fence, which acts as a grating. Notes that grating with zero spacing between the grating elements acts as a reflector. (MVL)

Suggests that physics students always have three questions when using force diagrams: (1) Why do I need one? (2) How do I draw one? and (3) How do I find the forces acting on a body? Provides a method to help students find answers to all three questions and understand force diagrams. (MVL)

Presents a model for the Slinky that allows for calculations that agree with observed behavior and predictions that suggest further experimentation. Offers an opportunity for introducing nonrigid bodies within the Galilean framework. (JRH)