This post was motivated by a tweet by Frank Noschese, reproduced below, to which I responded that I am a big fan of the “energy first” approach.

I must say that the approach I am advocating is not an idea of myself. I started thinking about it after reading a textbook by C. J. Fischer: “The Energy of Physics”, from which I derived my own approach. Fischer, in fact, introduces the concept of energy almost axiomatically, while I always prefer an approach based on experience.

In order to observe that free fall is a uniformly accelerated motion with acceleration g=9.8…

In my last post, I show how to obtain experimental data from Arduino via BLE. As promised, I now come to the collection and the interpretation of these data, in the case of an experiment in which a gas is subject to an isovolumetric process, i.e., a process in which the pressure p and the temperature T can change, while volume V remains constant.

The experiment is, indeed, very simple. You just need a BLE capable Arduino board, a barometric and temperature sensor, a power source and a jar. I used an Arduino MKR 1010 WiFi connected to a BME180…

In this post, I illustrate operation of an Arduino with BLE (Bluetooth Low Energy). As usual, physics being my field, I do not discuss a generic example (the equivalent of “Hello, World!”), but a concrete physics application. Sometimes, for brevity or clarity, I will not be rigorous, and purists may turn up their noses, but, as I read on a A. Zee’s books, “sometimes, too much rigor soon leads to rigor mortis”.

WARNING: I assume you are familiar with Arduino and C/C++ programming. If you are not, you will hardly understand the content of this article.

What I write here…

General relativity is one of the most technically difficult physics theories, as it requires uncommon knowledge and mathematical skills. However, it is possible to calculate the relativistic effects induced by the curvature of space-time with good precision, and even to derive its formula, with a few simple arguments.

We know from special relativity that time flows more slowly in a moving system than in a stationary one. Given t as the time elapsed aboard the moving system, the time elapsed for the stationary one is 𝛾t, with 𝛾>1. In other words, time for those moving flows more slowly. A striking…

Transistors are the building blocks of our electronic gadgets: from smartphones to computers, toys, cooking devices, cleaning tools, etc.

Despite their ubiquity, only a few people know about how they work. In fact, understanding their principles of operation is not so hard.

The diode: a transistor building block

In order to understand how a transistor work, we need to understand what a diode is. In fact, a transistor, in practice, is nothing but two diodes.

A diode, essentially, works as a valve for electric current. It lets a flow of electrons flow in one direction only, opposing the movement of electrons in the opposite direction, just…

In a previous post of mine, I illustrated a brief history of temperature scales in which I recalled that the reason for which 0 °F corresponds to －18 °C is that the latter was the lowest temperature that Daniel Gabriel Fahrenheit could achieve in his laboratory.

Such a temperature can be easily reached mixing water, ice and ammonium chloride. This was, in fact, a very common method to produce a frigorific mixture before the invention of the freezer. The melting of the salts in water, in fact, is a chemical reaction that requires heat to proceed. Indeed, as every Italian…

The most widely adopted temperature scale is the Celsius or centigrade scale. Nowadays, we use these terms as synonyms, but, in fact, they were not such, originally. The Celsius temperature scale was invented by Anders Celsius that, in 1742, proposed its use by publishing “Observationer om twänne beständiga grader på en thermometer” (Observations of two constant gradations on a thermometer).

In his paper, Celsius reported the observations, according to which the temperature of melting ice (marked as C) and that of boiling water (marked as D) appeared to be constant, if measured with a mercury thermometer.

He then proposed, on…

Most physics textbooks are similar. They differ (little) for the sequence and for the choice of the mathematical details with which topics are presented. Most authors and teachers do not even ask themselves why they illustrate topics that way. Apparently, there is only one way to introduce something.

I believe this is not true. At least, I find stimulating trying to find alternative ways to introduce something in a different way. It is a difficult task, of course, and that is, maybe, why it is rewarding.

Let me be clear: I am not stating that alternative ways of teaching something…