Observing the bouncing of a marble on a table is a rather common experience. The tic-tac sound of the rigid ball, nevertheless, carries quite a pleasant surprise. In fact, by measuring the total time of bouncing [delta]t, the coefficient of restitution can be estimated. As is well known, in an inelastic collision the kinetic energy is not…

Similar to how stealth materials were developed to reduce the radar wave energy returning from an aircraft, here we explore a low-cost laboratory demonstration that uses similar principles to prevent detection of an object by an ultrasonic sensor. This demonstration setup can be used as a starting point to encourage students to explore the surface…

It is well known that when two waves are added they produce beats. These beats are the amplitude modulation of the initial waves and occur periodically at a rate equal to the frequency difference of the two waves. Acoustical beats arise from sound waves of nearly equal frequencies. Optical beats arise from the interference of two light waves of…

Resistor-capacitor (RC) circuits are a popular topic for both theoretical discussion and experimental investigation in introductory physics. This article presents a novel approach to studying such circuits using a piezoelectric buzzer. A capacitor is discharged through a resistor and the buzzer, and the intensity of the sound produced by the…

In the present theoretical study, we introduce the entropy concept into Chi's ontological shift theory. Chi distinguishes between two categories of process phenomena, direct and emergent, and claims that incorrectly considering emergent processes as direct ones is one of the sources of students' robust scientific misconceptions. The present study…

Science education research has shown that students use causal reasoning, particularly the model "agent--instrument--object," to explain or predict the outcome of many natural situations. Students' reasoning seems to be based on a small set of few intuitive rules. One of these rules quantitatively correlates the outcome of an experiment…

New media technology becomes more and more important for our daily life as well as for teaching physics. Within the scope of our N.E.T. research project we develop experiments using New Media Experimental Tools (N.E.T.) in physics education and study their influence on students learning abilities. We want to present the possibilities e.g. of…

A common moving-coil (dynamic) loudspeaker is a device very suitable for teaching the general features of oscillating systems. As an addition to a previous paper (Kraftmakher 2009), this paper includes the following topics: (i) a new design of the optical sensor for measuring the cone oscillations; (ii) positive feedback and self-excited…

People who live near wind turbines complain of symptoms that include some combination of the following: difficulty sleeping, fatigue, depression, irritability, aggressiveness, cognitive dysfunction, chest pain/pressure, headaches, joint pain, skin irritations, nausea, dizziness, tinnitus, and stress. These symptoms have been attributed to the…

Thermoacoustic instability is defined as the excitation of acoustic modes in chambers with heat sources due to the coupling between acoustic perturbations and unsteady heat addition. The major objective of this paper is to achieve accurate theoretical results in a thermoacoustic heat transfer process. We carry out a detailed heat transfer analysis…

A basketball bounced on a stiff surface produces a characteristic loud thump, followed by a high-pitched ringing. Describing the ball as an inextensible but flexible membrane containing compressed air, I formulate an approximate theory of the generation of these sounds and predict their amplitudes and waveforms. (Contains 3 figures.)

It is well known that the pitch of the sound produced by an excited glass shell can be tuned by adding some liquid in it. In this paper, it will be proved that the distribution of the liquid inside the shell plays a crucial role in this frequency shift. Thus it provides another way to tune the pitch of the sound by modifying the liquid…

A common moving-coil loudspeaker is useful for learning harmonic motion. A simple optical method is used to observe free and forced oscillations of the diaphragm of a loudspeaker. With a lock-in amplifier and data-acquisition system, the frequency response of the loudspeaker and its electrical impedance are automatically recorded versus frequency.…

Teaching about light and sound is to teach about the processes of hearing and seeing. In considering the kinds of leading questions that we might ask in teaching, I suggest that a rethinking of how we consider the contribution of the energetic descriptions to this area will probably help to make these questions more fruitful. A subtly changed…

The Celsius and Kelvin temperature scales, we tell our students, are related. We explain that a change in temperature of 1 degree C corresponds to a change of 1 Kelvin and that atoms and molecules have zero kinetic energy at zero Kelvin, -273 degrees C. In this paper, we will show how students can derive the relationship between the Celsius and…