In this research, an educational approach to the concept of energy is proposed. It is based on the history of physics. In 1854 Hermann Hemlholtz gave a popular lecture on the recent discovery that energy is conserved. Such lecture is used as a guide to introduce the pupils within several nuances of this concept. Not much mathematics is used, so…

What happens when a perfectly elastic ball collides with a completely inelastic ball? It is shown that the outcome depends on the stiffness of each ball. A standard textbook problem in mechanics is to calculate the outcome of a head-on collision between two balls using conservation of momentum and kinetic energy. It is easily shown that the…

Teaching special relativity to lower-division students is challenging because results such as time dilation, length contraction, and frame dependence of simultaneity are counterintuitive. The literature is extensive, so only a brief list is given here, with articles divided roughly between discussions of general principles and calculations applied…

The problem of an electrically charged pendulum above a grounded conducting surface is examined using traditional analyses, such as forces, energy, and torque. The system was numerically modelled using a finite difference method and analysed. A number of classroom activities have been suggested.

A loop-the-loop experiment usually involves a ball rolling around a vertical loop. A different version of the experiment is described where a nut was allowed to slide around a vertical loop. In both experiments there is a large decrease in kinetic energy when the ball or the nut first enters the loop.

In this paper, we propose a simple yet generic and versatile method to measure the position of a moving body as a function of time. Apart from very basic equipment such as carts and wheels, only a laser pointer or a similar device and a smartphone are necessary. By attaching a source of light to a cart and video filming its movement on a…

Resonance is an important, and rather dramatic, phenomenon in physics. The mechanical case of a mass-spring oscillator is generally the first example that students encounter in introductory courses. In electromagnetism, the resonance in driven RLC circuits is presented in analogy with mechanics, since the mathematical equations describing them are…

A rocket in free space accelerates from rest by continuously expelling fuel; as its speed increases, its mass decreases. At what speed (and remaining mass) does the rocket carry maximum momentum? Maximum kinetic energy? The answers provide insights into the dynamics of variable-mass systems, and have applications to planetary defense that are…

A classical mechanical structure with an internal degree of freedom is shown to reflect off a potential well. Such behavior is impossible for point-like or rigid classical particles. This numerical study provides insight for students studying internal energy and degrees of freedom.

In this paper, we seek to evaluate the extent to which students can follow a deductive reasoning chain when it is presented to them. A great deal of instruction in introductory physics courses is centered on presenting students with a logical argument that starts from first principles and systematically leads to a particular conclusion. This…

The electric field inside a uniformly charged long cylindrical shell is a standard example discussed in introductory university physics. The field is zero inside the cylinder; outside of the cylinder, the field behaves like a long wire at the center carrying the same amount of charge per unit length, analogous to that of a uniformly charged…

Work and mechanical energy is a fundamental topic in introductory physics. Studies in existing literature have shown that students have difficulties in understanding work and mechanical energy, particularly the topic of work-energy theorem. To study students' knowledge integration in learning work and mechanical energy, a conceptual framework…

Experimental results are presented on the collision of a superball with two different wood blocks. The results are in reasonable agreement with a simple collision model where kinetic energy is conserved, but better agreement is obtained if a small loss of kinetic energy is assumed, as observed. The physics is slightly more complicated than the…

A significant goal when teaching at the secondary education level is to present the generality of the procedures that are being used to describe a wide range of different physical phenomena. However, this approach is abandoned by physics instructors in many cases since the general mathematical background needed to present the above generality is…

The photoelectric effect consists of electrons emerging from the region near the inner surface of a metallic solid toward the outside vacuum, when the metal surface is illuminated. The effect depends on the frequency of the light waves and the properties of the metal surface. In particular, a minimum or "threshold" frequency of light is…