To explain experiences of riders of rotating systems, such as a merry-go-round, some physics educators have employed the concept of 'centrifugal force.' However, others have suggested that the term is unnecessary in explaining experiences in rotating systems and that it encourages misconceptions surrounding circular motion dynamics. Owing to this…

The various aspects of projectile motion have been analyzed many times in this journal. As a sample, over the years, authors have investigated particular details of the path of a projectile and different situations for launching projectiles. Others have written about a nifty way to determine the maximum height of a projectile, finding the range of…

Modern MEMs gyros/accelerometers allow the angular velocity of pendula to be precisely measured and the angular acceleration to be calculated. For a compound pendulum, "I"[subscript p][umlaut over theta]=-"mga" sin[theta]Ip[umlaut over theta]=-mgasin[theta], where "a" is the distance of the center of mass from the…

Background: Recognizing the relatively few studies that have explored university students' understanding and alternative conceptions in linear and circular motion as well as the relatively few studies that have used 2-dimensional multiple-choice questions (MCQs) in the science education literature, this study set out to contribute to these areas.…

Difficulties in understanding physics concepts are often experienced by students such as in the material of regular uniform motion. This study aims to describe the mental models of first-year secondary school students on regular straight-line motion. This research utilized a case study method of 167 students at the secondary level with an average…

We describe a simple, intuitively appealing interpretation of the observed ellipsoidal shape of the rotating Earth: it is that surface everywhere perpendicular to the net force upon it.

On 24 June 1994 at Fairchild Air Force Base, during practice for an air show, a low-flying B-52H aircraft banked its wings vertically and crashed. Emphasizing the activity of modeling drag and gravity, these notes examine the possibility of recovery with several models. First, with algebra, historical data lead to a model where in a free fall near…

This paper has a pedagogical aim. Indeed, by using the relativistic velocity-addition and Einstein's equivalence principle (EEP), we want to analyse in a simple way the physics of time on a rotating non-inertial frame. We use a didactic approach considering four friends. The first is in the laboratory, the second at rest on the disk at radius r,…

Acceleration of moving objects is usually measured by photoelectric gates. In this paper, a method of acceleration measurement is proposed by pasting white card stock and black tape on a pulley and then using an Arduino to time the motion. This method only needs one photoelectric sensor to measure the acceleration. In contrast, using photoelectric…

Inspired by a commercially produced scattering experiment that was popular beginning in the 1960s, we have developed a Nerf-projectile-based educational activity to demonstrate the basics of particle scattering experiments.

If an empty coffee cup is spun on a horizontal surface about a vertical axis in an anti-clockwise direction, then the whole cup rotates slowly backwards, in a clockwise direction, about a vertical axis located outside the cup. Clues to this curious behaviour are presented by comparing it with other spinning objects.

How many vertical jumps does it take to jump off of a rotating merry-go-round (MGR)? The answer is hidden in the expression: "r[subscript n]" = "r[subscript 0]" (1 + ["beta superscript 2") ["superscript n/2"]. When you make a vertical jump on a train moving on a straight line at constant speed (inertial…

The center of mass (CM) is an abstract quantity but essential as a reference point used to understand the position and movement of an object or a system of objects. Many researchers have used video recordings to analyze and understand the movement of objects in a system. In a system with colliding objects, the motion can be obtained precisely from…

The use of toys as teaching aids in physics classrooms has a rich history, and the role of play in science education is a well-established line of research. Much of what has been written on the topic has included discussions of specific toys and the implications of using those toys to teach physics. One of the toys from my childhood that seems to…

The relativistic addition of velocities is usually introduced early in the study of Einstein's special theory of relativity. The equations are simple enough, but randomly chosen velocities lead to unwieldy calculations that can dishearten the student. This paper presents tables of velocity components in two dimensions, composed of five or fewer…