A Brief History of Entropy pt. 4 – How to Avoid the Communication Breakdown

Pontecchio, Italy, December 8th 1895 A gunshot in the distance marked the beginning of the communication era based on electromagnetic waves. A sunny springtime afternoon, a villa in the heart of Italy's countryside. Guglielmo, son of the marquise Giuseppe Marconi and Annie Jameson (perhaps you tasted the famous whiskey brewed by her father) is a very …

A Little Bit of Entropy

I'm reading a very interesting book written by Seth Lloyd called "Programming the Universe: a quantum computer scientist takes on the Cosmos". Highly recommended! I enjoyed in particular how entropy is compared to a spreading disease: a disease of ignorance. What is it all about? Let me explain briefly. From statistical mechanics, entropy is a measure …

Come fa una barca a vela a risalire il vento?

Se non ne eravate già al corrente, la prima notizia è che una barca a vela può risalire il vento. Questo fatto viene riassunto di solito nei cosiddetti diagrammi polari, che mostrano la velocità massima alla quale l’imbarcazione può viaggiare relativamente alla direzione del vento reale: Come si vede, la velocità massima per un angolo …

My First Arduino-based Robot

My First Arduino-based Robot Finally, I managed to assemble my first Arduino-based robot. I bought it from this Italian online shop. They provide all the instructions as well, but you also need some tools (screwdrivers, soldering tool, etc.) and some patience. It works fine! Thanks to a quite basic IR sensor, this small rover can …

Re-discover Neptune with Processing

As we saw in the previous post, it's quite easy to make even not-so-basic physics simulations with Processing and Jeffrey Traer's library for physics. This time we'll give a closer look to the discovery of Neptune. We won't be really accurate here, I just want to give you the gist of it. Reverse engineering the …

What’s Inertia? Ask Feynman!

He had taught me to notice things and one day when I was playing with what we call an express wagon, which is a little wagon which has a railing around it for children to play with that they can pull around. It had a ball in it—I remember this—it had a ball in it, …

Constrained Inclined plane

Provate a risolvere questo esercizio! Una perlina di massa m è vincolata a muoversi lungo un filo di lunghezza L posto nel piano verticale yz sotto l'effetto della sola forza di gravità, partendo da ferma nel punto P. Calcolare: Con che velocità arriva nel punto Q Quanto tempo impiega ad arrivare in Q Dimostrare che se i …

The Felix Baumgartner Equation

Introduction We want to describe, even in not with a fully realistic accuracy, the motion of Felix Baumgartner while...falling from the sky as it happend on October 14, 2012. To do this, we well make use of Wolfram’s Mathematica. The Austrian daredevil jumped from a helium ballon at an altitude of 39,014 m and opened …

Calore Specifico di un Termostato Ideale

Per termostato ideale si intende un corpo in grado di fornire calore pur mantenendo una temperatura strettamente costante. Questa e' una utile approssimazione nel caso in cui si vogliano studiare le trasformazioni termodinamiche di un corpo (ad esempio un fluido) o di una macchina termica, con particolare attenzione alle sue variazioni di temperatura. Infatti, trasformazioni reversibili …

Summary: Electrostatics in Free Space

A brief summary of the basic equations for electrostatics in empty space Dielectric constant: $latex \epsilon_0=8.854*10^{-12} ~C^2N^{-1}m^{-2}$ Electron charge: $latex e=1.6*10^{-19}~C $ Coulomb's law of attraction: $latex \vec{F}=\frac{1}{4\pi \epsilon_0}\frac{q_1q_2}{r_{12}^2}\hat{r}=k_0\frac{q_1q_2}{r_{12}^2}\hat{r}= k_0\frac{q_1q_2}{r_{12}^3}\vec{r}$ Electrostatic field: $latex \vec{E} = \frac{1}{q}\vec{F} $ Flux of the electrostatic field: $latex \Phi_S(\vec{E}) = \int \vec{E}\cdot \hat{n}dS=\int_S \vec{E}\cdot\vec{dS} $ Gauss' theorem:  $latex \Phi_S(\vec{E}) = \int …