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US undergraduate students who participate in laboratory sections of physics courses show no discernible improvement in their exam scores over students who participate in only the lecture sections. In a [...]

To characterize the evolution of student understanding better than what is possible by pre-and post-testing, we posed simple conceptual questions several times per week to separate, randomly selected groups of introductory physics students. This design avoids issues of retesting and allows for tracking of student understanding of a given topic during the course with a resolution on the order of days. Based on the data from over 1600 students over five quarters, we found significant and interesting changes in performance on time scales of days and weeks. We found that the response curves of performance versus time can be divided into four categories: flat (no change), step-up, step-up and decay, and step-down. We examined changes on a 1 day time scale and found that changes in performance did not coincide with relevant traditional lectures or laboratories, but coincide with due dates of relevant on-line homework that provides immediate feedback. This method is well suited to measuring the effect of particular instructional events as well as providing insight into the nature of student understanding and learning. [c] 2010 American Association of Physics Teachers. [DOI: 10.1119/1.3384261]

We discuss the two-capacitor problem found in many introductory physics texts in which there appears to be missing energy in an ideal, zero-resistance circuit, following the sudden charging of one capacitor from another. The paradox of this missing energy is traditionally ascribed to finite-resistance wires, the initial assumption of an ideal circuit and the rapid nature of the charging notwithstanding. By treating radiative effects in the simplest approximation, we show that the paradox is really nothing more than an inappropriately applied lumped-parameter model. In particular, we show that in the zero-resistance circuit, radiation fully accounts for all of the energy lost. To explore radiative effects in more realistic circuits, we also discuss numerical examples that include a small resistance and inductance. [DOI: 10.1119/1.1435344]

A step-by-step description is presented of the equipment and technique which can be used by sixth form students to accurately measure acceleration due to gravity. The use of a microcomputer to analyze the experimental data is discussed.

We review various folding problems arising in the physics of membranes and polymers. These are (1) the phantom folding of tethered membranes, i.e. the two-dimensional lattice folding; (2) the phantom folding of fluid membranes, i.e. the folding of tessellations of arbitrary genus; (3) the self-avoiding folding of polymers, i.e. the meander problem. All three problems are found to be related to coloring problems and possess .one kind of underlying integrable structure, in different guises. Many mathematical results follow from taking advantage of this fact.

A critique of a previous theory regarding circular mass movement is presented, focusing on the determination of why a hoop can become airborne. The critique includes reasoning regarding a no-slippage condition, and static and kinetic friction between the support surface and the hoop.

Physic teachers can utilize physlets, small scriptable, single concept applets written for teaching physics, to help students visualize and interact with electrostatic phenomena. Six exercises in electrostatics are explained and are relatively easy to implement through the use of an Internet connection and Java applets. The exercises include interpreting different representatives in electric fields, electric flux experiments and several concepts in electrostatics and mechanics.

The Maxwell wheel is generally used to demonstrate inertia of a disc to introductory physics students. When the Maxwell wheel is attached to a personal computer, through a position sensor and a force sensor, the system evolution in time can be observed kinematically and dynamically.

US physics courses fail to challenge students because the provided problems are solvable and just train skills. However, traditional problem sets can be modified to make them more difficult and to truly test their skills in ways a mainstream problem does not using techniques from the Soviet Olympiad. Problem sets for vector addition and components, reference frames and approximation selection are provided.

Newton's law of universal gravitation and some undergraduate physics and mathematics principles can be explored through five questions concerning the gravitational forces between familiar particles and objects. The questions are presented with discussions and answers. The forces between planets, falling objects and a newborn and the obstetrician are explored in an interesting manner.

Real-world data acquisition can be easily performed using a laptop computer and a digital multimeter designed to work with a computer. Acceleration, temperature and velocity as functions of time can be measured in the field if the proper sensors are used. A laboratory photogate can successfully measure a bicycle's speed directly if attached to the tire and rim. Acceleration can be measured using a force transducer that is battery operated. Bicycle brake pad temperature can be measured with a type K thermocouple. Experiment procedures are included.

Hands-on experiments in introductory physics have mixed support and most teachers agree they need to be revised. One possible revision uses the guided discovery approach and emphasizes understanding the physics concepts over finding the correct answer. This approach can be used for many of the traditional exercises such as the collapsing can. Students are given the experiment as a take-home exercise and must write a lab report on what they have discovered. This approach helps students understand physics while giving them confidence in their own skills. An activity worksheet is included.

The US hosted for the first time the International Physics Olympiad in Jul 1993 at the College of William and Mary in Williamsburg, VA. The annual competition engages the world's pre-college students in two half-day examinations that are challenging and interesting to create.

Coupled mechanical oscillators make useful interactive corridor displays because they demonstrate physics principles that are evident to the viewer and do not require a lot of space. The displays should be staggered so that all oscillators cannot be activated at the same time and explanations included to tell viewers what to look for and what is happening. Some effective demonstrations are: sympathetic oscillation, symmetrically started or oppositely started oscillators and a Wilberforce 'pendulum.'

A simple experimental setup can be used to demonstrate the storage of macroscopic dust particles in a 'Paul trap.' The trap is operated at atmospheric pressure, which results in an efficient 'cooling' of the stored particles. Under these conditions, a single anthracene dust particle has been confined for over 2 months. The device is well suited to show the formation of ordered structured when a number of 'cooled' species are trapped. Due to its overall simplicity, the setup can be used in lectures, student laboratories, etc.

A solution is presented to the following problem: Describe the motion of a tank car initially at rest once an off-center drain opens. The tank car rolls without friction on a horizontal surface, and the water flows out of the drain vertically in the rest frame of the car.

With the help of a hand-held jigsaw and a tin of syrup, the little known dynamically stablized inverted liquid experiment can be demonstrated to large clases. Lengthy effective potential arguments are short-circuited by a simple inverted U-tube theory accessible to most. The role of viscosity and wall effects is discussed. The first dynamic stabilization experiment with water is reported.

An experiment is presented for the phenomena of an inclined stick falling to the ground before a ball does when the ball is released from the same height as the end of the inclined stick.

Four problems involving the calculation of centripetal acceleration are described. Multiple solutions are also described and discussed.

An experiment is described that teaches students the principles of stellar interferometry using binoculars or a small telescope to measure the sized of distant street lights. This experiment shows students the principles behind optical interferometry and how it is used with much more powerful equipment to measure stars.

A mathematical formula is introduced that will improve the data received from an experiment demonstrating Newton's second law of gravitational forces.

Secondary school students of 16 years of age should have sufficient familiarity with the calculations which will enable them to study data concerning the El Nino effect. The data concerns the difference in sea level between the western and eastern Pacific ocean, and the volume of water in the resulting wedge shape. Calculations using this data give the heat energy absorbed by the water. Further calculations reveal the mass of air above the water which is affected by this change, and give an idea of the scale of the El Nino effect on surrounding economies.

A physic experiment examines the illusion of motion as it appears from examining spokes on wheels. A stagecoach rolling forward can appear to have wheels that are turning slowly backward unless the spokes are deliberately spaced unevenly apart.

A collection of small tried-and-true demonstrations are presented to help physics teachers with exciting lessons that don't take a great deal of preparation or equipment. Many of the demonstrations can be conducted by using supplies that are usually found in a lecture room and illustrate or simulate mechanics, electricity, waves, sound or optics.

Often the concept of electricity causing televisions, computers and Nintendos to function is not completely understood by studying current and voltage through bulbs and battery experiments. By using a measuring tool call the Watt/Watt-Hour Meter, the study of energy explicit and applicable to real life.

Three critical thinking exercises can give physics students a new perspective on Newton's law of universal gravitation by changing the physical constants or laws. The exercises involve the gravitational effect of a thin spherical shell of uniform mass density on objects within and without the sphere. The one-, two-, and three-dimensional cases are considered.

Examiners from the NEAB examining board in the UK expressed surprise that A-level students were not able to answer correctly a seemingly simple question asking them to explain Newton's second law of motion. However, an examination of advanced physics texts and advanced mathematics texts demonstrates that the law is defined differently in the two subjects. Examiners should amend the core for these two linked subjects to clear the confusion for students.

A question concerning the weight of a falling object in a mine shaft posed in a junior-high Science Bowl failed to consider all the influences on gravity that would make the object heavier at either end of the shaft. These influences include centrifugal force, air buoyancy and the missing earth from the shaft while the main question of where maximum gravitational force is present on the Earth cannot be easily resolved. An exploration of the question is presented that determines necessary local density parameters for a heavier weight at either the top or bottom of the shaft.

The practical examination taken at Hammersmith and West London College in May 1992 for the London University Advanced Level examination in physics was made up of four tasks. An analysis of the results has been made to see if the organisation of the examination interacted with the design of the four experimental stations to benefit some pupils more than others. There was a marked difference in the mean scores between the four groups, and it did appear that some aspect of the first experiment disadvantaged pupils who started on it. The possible solutions to problems caused when examination centres use a rotating technique for practical examinations are discussed.