The aim of this research was to design a simple experimental device to see electric field force lines using common components which are readily available in everyday life. A solution of baby oil was placed in a plastic container, 4.5 × 4.5 × 1 inches, with both ends of the electrodes (metal wire) immersed in the solution at a depth of 0.2 inches.…

We investigate a water-filled bottle rolling down an incline and ask the following question: is a rolling bottle better described by a model ignoring all internal motion where the bottle is approximated by a material point sliding down an incline, or is it better described by a rigid solid cylinder rolling down the incline without skidding? The…

Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

Giraffes face unique challenges for drinking due to their long necks. In this article we use evidence from videos, size estimates, and elementary fluid mechanics to make a strong case for a plunger pump mechanism moving water up from their lips to their shoulders.

Center of mass (CM) is an important concept in physics, especially when studying extended bodies. For example, general motion of an extended body can be considered as the sum of the translational motion of the CM plus other types of motion about that CM. CM also can be regarded as a "balance point" so that a system supported at its CM…

The aim of this paper is to provide a way of teaching the factors that affect resistance using mechanical pencil leads and the brightness of the light given out by a light bulb connected to an electrical circuit. The resistance of a conductor is directly proportional to its length (L) and inversely proportional to its cross-sectional area (A).…

Variations of a demonstration in which a sheet of paper or a bead is levitated in a grazing stream as from one's breath have been published in several sources. Even a massive ball can be deflected into the robust flow from a leaf blower. The attraction is surprising because it is often quite stable and seems to conflict with the familiar transient…

Through a century of work, physicists have refined a model to describe all fundamental particles, the forces they share, and their interactions on a microscopic scale. This masterpiece of science is called the Standard Model. While this theory is incredibly powerful, we know of at least one particle that exhibits behaviors that are outside of its…

The conjunction of three events has encouraged me to devote significant time to thinking about the pedagogical framework in my introductory courses. The three events were: doing a workshop addressing the Advanced Placement restructuring of the Physics B course with a stronger focus on critical thinking, finding out that "The Physics…

If the end of a long chain, which is contained in an elevated beaker, is dropped over the edge of the beaker and falls, it is observed that as the speed of the chain increases the chain rises to form a loop well above the top of the beaker. The name "chain fountain" has been applied to this phenomenon. In this study the dependence of the…

An important concept that is presented in the discussion of Newton's law of universal gravitation is that the gravitational effect external to a spherically symmetric mass distribution is the same as if all of the mass of the distribution were concentrated at the center. By integrating over ring elements of a spherical shell, we show that the…

This paper presents the development of a conductive gel that can be used to measure the electrical potential differences on its surface, and has enough consistency to plot equipotential lines. It has a gelation time of less than 10 min, and is suitable for implementing learning experiences in a physics teaching laboratory in a 90 min session. To…

With a rod, cord, pulleys, and slotted masses, students can observe and graph exponential growth in the cord tension over a factor of increase as large as several hundred. This experiment is adaptable for use either in algebra-based or calculus-based physics courses, fitting naturally with the study of sliding friction. Significant parts of the…

The primary objective of the activity presented here is to allow students to explore the frequency components of various simple signals, with the ultimate goal of teaching them how to remove unwanted noise from a voice signal. Analysis of the frequency components of a signal allows students to design filters that remove unwanted components of a…

We report on five experiments investigating response choices and response times to simple science questions that evoke student "misconceptions," and we construct a simple model to explain the patterns of response choices. Physics students were asked to compare a physical quantity represented by the slope, such as speed, on simple physics…