Bounded by the statements of Feynman and Galileo, I describe certain tricks that can be useful for the teaching of physics. In particular, I describe the calculation of the center of mass (centroid) of an arc of circumference and a circular sector. For this purpose, I also use Pappus's theorems. An Appendix is available with Archimedes' method to…

In the present work, we demonstrate the phenomenon of temperature difference power generation, which is achieved by the reversible conversion between thermal and electrical energy.

In the movie Gravity, American astronaut and scientist Dr. Stone (Sandra Bullock) is on a spacewalk when tragedy suddenly strikes. An ever-increasing field of debris caused by a destroyed spy satellite damages the Hubble and Space Shuttle and quickly wipes out their mission. Dr. Stone spends the rest of the movie trying to find a ride back home.

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…

In physics education, the topic of electromagnetic induction is an important but also challenging topic for many students. The early introduction of formulae, e.g., Faraday's law of induction, seems to hinder rather than to foster the understanding of the topic's underlying principles. In this paper, we present the basic idea for a teaching…

It has long been suspected by general relativists that physicists who do not specialize in general relativity (GR) believe that special relativity (SR) is incapable of modeling dynamics within accelerated reference frames. Consequently, many physicists may conclude that certain phenomena, such as time dilation due to acceleration, can only be…

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.

The Wilson cloud chamber is an apparatus used for detecting and observing the trails of alpha/beta rays or even cosmic rays in saturated gas conditions. The principle of this device is based upon the powerful ionization of the aforementioned rays within the medium. This article will provide instruction for creating a classic version of the cloud…

The statics of fluids may seem simple at first but often poses problems for students when it comes to applying it to concrete cases. Despite its relatively simple laws, some subtleties, mainly related to the elastic characteristics of a fluid, must be noted. This elasticity allows the pressure exerted in a part of the fluid to propagate in its…

It is well known that the needle of a compass in a magnetic field deflects, and that a compass near a conductive wire carrying a stable electric current deflects its needle. The only explanation of this observation is that the current-carrying wire creates a magnetic field around it. The strength of the magnetic field at any point near the wire…

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.

With the development of digital technology, plentiful sensors are embedded in the smartphone, which makes it a valuable tool for teaching elementary experimental physics. For instance, the magnetic field sensor of the smartphone has been used to measure gravitational acceleration by measuring the magnetic pendulum's oscillation period. The…

The early 20th century marked a number of transformational experimental and theoretical discoveries in physics. Among them is one that is often neglected in the introductory physics curriculum, which revolutionized our understanding of the molecular world. Evidence for the thermal motions of atoms was first observed by Perrin in 1909, which had…

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…