When one end of a taut horizontal elastic string is shaken repeatedly up and down, a transverse wave (assume sine waveform) will be produced and travel along it. College students know this type of wave motion well. They know when the wave passes by, each element of the string will perform an oscillating up-down motion, which in mechanics is termed…

In order to increase the knowledge of locomotor disturbances in children with autism, and of the mechanism underlying them, the objective of this exploratory study was to reliably and quantitatively evaluate linear gait parameters (spatio-temporal and kinematic parameters), upper body kinematic parameters, walk orientation and smoothness using an…

Anything that can capture the interest of students can be used to enhance the teaching of physics, and sport is practised, watched and followed fanatically by almost every young person. At the same time, in recent years, a wealth of research data has become available from the field of sports science. The purpose of this article is to draw from…

A simple variational property concerning the velocity distribution of a set of point particles is illustrated. This property provides a full characterization of the velocity distribution which minimizes the kinetic energy of the system for prescribed values of linear and angular momentum. Such a characterization is applied to discuss the kinetic…

Based on relativistic velocity addition and the conservation of momentum and energy, I present simple derivations of the expressions for the relativistic momentum and kinetic energy of a particle, and for the formula E = mc[superscript 2]. (Contains 5 footnotes and 2 figures.)

The trajectories of the molecules in an ideal gas and of the ball in a soccer game are compared. The great difference between these motions and some similarities are discussed. This example could be suitable for discussing many concepts in kinetic theory in a way that can be pictured by students for getting a more intuitive understanding. It could…

An interstellar Bussard ramjet is a spaceship using the protons of the interstellar medium in a fusion engine to produce thrust. In recent papers, it was shown that the relativistic equation of motion of an ideal ramjet and that of a ramjet with radiation loss are analytical. When a mass loss appears, the limit speed of the ramjet is more strongly…

Written by Jim and Jane Nelson, Teaching About Kinematics is the latest AAPT/PTRA resource book. Based on physics education research, the book provides teachers with the resources needed to introduce students to some of the fundamental building blocks of physics. It is a carefully thought-out, step-by-step laboratory-based introduction to the…

We physics teachers are forever in search of real-life applications of the theoretical concepts we teach. In mechanics we often utilize vehicle motion exercises, yet most textbook problems involving these are rather tame and deal with constant acceleration. What often captures the imagination of students is the actual performance of cars they…

The generalized potential of the inertial forces acting on a holonomic system in an accelerated reference frame is derived in a way which admits a simple physical interpretation. It is shown that the generalized potential refers to all the inertial forces and, apart from the very special case of a uniformly rotating frame, it is impossible to…

The effects of two types of two well-established microcomputer-based teaching methods were examined for their effect on teaching high school students kinetics. The use of data acquisition probeware and digital video analysis were studied for their impact on students' conceptions and ability to interpret graphical relationships to real world…

Ah, springtime, and young people's thoughts turn to... baseball, of course. But this column is not about "how" to throw a curveball, so you'll have to look that up on your own. Here, the focus is on the "why" of the curveball. There are two different things that cause a spinning ball to curve. One is known as the "Bernoulli effect" and the other…

This paper examines the use of the 3-D virtual world Second Life to explore basic mechanics in physics. In Second Life, students can create scripts that take advantage of a virtual physics engine in order to conduct experiments that focus on specific phenomena. The paper explores two particular examples of this process: (1) the movement of an…

The Sun's atmosphere is a highly structured but dynamic place, dominated by the solar magnetic field. Hot charged gas (plasma) is trapped on lines of magnetic force that can snap like an elastic band, propelling giant clouds of material out into space. A range of ground-based and space-based solar telescopes observe these eruptions, particularly…

Video analysis of motion has been in use now for some time. However, some teachers may not have video equipment or may be looking for innovative ways to engage students with interesting applications at no cost. The recent advent of YouTube offers opportunities for students to measure kinematic properties of real-life events using their computers.…