arXiv subjects

Roberto De Luca

Publications and source records attributed to Roberto De Luca.

7 recordsLinked to original sources

arXiv2025

Which Rope Breaks? A Study of Tension Distribution in Multi-Rope Systems

We investigate the tension distribution in systems of mass-less ropes under different loading conditions. For a two-rope system, we demonstrate how the breaking scenario depends on the applied force dynamics: rapid pulling causes the lower rope to break, while gradual pulling leads to upper rope failure. Extending to a three-rope Y-shaped configuration, we identify a critical angle $θ_{C}=60^{\circ}$ that determines which rope breaks first. When the angle between the upper ropes exceeds this critical value, the upper ropes fail before the lower one. We further analyze how an attached mass at the junction point modifies this critical angle and establish maximum mass limits for valid solutions. Our results provide practical insights for introductory physics students understanding static forces and system stabilities.

physics.ed-ph↗

arXiv2020

Some insight into Feynman's approach to electromagnetism

We retrace an ab initio relativistic derivation of Maxwell's equations that was developed by Feynman in unpublished notes, clarifying the analogies and the differences with analogous treatments present in the literature. Unlike the latter, Feynman's approach stands out because it considers electromagnetic potentials as primary, reflecting his ideas about the quantum foundations of electromagnetism. Some considerations about the foundations of special relativity, which are naturally suggested by this approach, are given in appendix.

physics.hist-ph↗

arXiv2019

Feynman's different approach to electromagnetism

We discuss a previously unpublished description of electromagnetism outlined by Richard P. Feynman in the 1960s in five handwritten pages, recently uncovered among his papers, and partly developed in later lectures. Though similar to the existing approaches deriving electromagnetism from special relativity, the present one extends a long way towards the derivation of Maxwell's equations with minimal physical assumptions. In particular, without postulating Coulomb's law, homogeneous Maxwell's equations are written down by following a route different from the standard one, i.e. first introducing electromagnetic potentials in order to write down a relativistic invariant action, which is just the inverse approach to the usual one. Also, Feynman's derivation of the Lorentz force exclusively follows from its linearity in the charge velocity and from relativistic invariance. Going further, i.e. adding the inhomogeneous Maxwell's equations, requires some more physical input, and can be done by just following conventional lines, hence this task was not pursued here. Despite its incompleteness, this way of proceeding is of great historical and epistemological significance. We also comment about its possible relevance to didactics, as an interesting supplement to usual treatments.

physics.hist-ph↗

arXiv2017

A hydrodynamic model for cooperating solidary countries

The goal of international trade theories is to explain the exchange of goods and services between different countries, aiming to benefit from it. Albeit the idea is very simple and known since ancient history, smart policy and business strategies need to be implemented by each subject, resulting in a complex as well as not obvious interplay. In order to understand such a complexity, different theories have been developed since the sixteenth century and today new ideas still continue to enter the game. Among them, the so called classical theories are country-based and range from Absolute and Comparative Advantage theories by A. Smith and D. Ricardo to Factor Proportions theory by E. Heckscher and B. Ohlin. In this work we build a simple hydrodynamic model, able to reproduce the main conclusions of Comparative Advantage theory in its simplest setup, i.e. a two-country world with country A and country B exchanging two goods within a genuine exchange-based economy and a trade flow ruled only by market forces. The model is further generalized by introducing money in order to discuss its role in shaping trade patterns. Advantages and drawbacks of the model are also discussed together with perspectives for its improvement.

q-fin.GN↗

arXiv2017

The effect of the behavior of an average consumer on the public debt dynamics

An important issue within the present economic crisis is understanding the dynamics of the public debt of a given country, and how the behavior of average consumers and tax payers in that country affects it. Starting from a model of the average consumer behavior introduced earlier by the authors, we propose a simple model to quantitatively address this issue. The model is then studied and analytically solved under some reasonable simplifying assumptions. In this way we obtain a condition under which the public debt steadily decreases.

econ.GN↗

arXiv2017

Propensity to spending of an average consumer over a brief period

Understanding consumption dynamics and its impact on the whole economy and welfare within the present economic crisis is not an easy task. Indeed the level of consumer demand for different goods varies with the prices, consumer incomes and demographic factors. Furthermore crisis may trigger different behaviors which result in distortions and amplification effects. In the present work we propose a simple model to quantitatively describe the time evolution over a brief period of the amount of money an average consumer decides to spend, depending on his/her available budget. A simple hydrodynamical analog of the model is discussed. Finally, perspectives of this work are briefly outlined.

q-fin.GN↗

arXiv2016

Search for a Dark Matter component

In this paper, after reviewing some of the most important concepts about Dark Matter (DM) and methods of its registration, in particular by using SQUIDs, we focus on two main problems. First, the possible mechanism of magnetic moment origin for DM particles, in the form of neutralino, is discussed: the presence of a magnetic moment means the existence of a new kind of interaction, whose corresponding cross section is estimated. Second, a simple uniform model for DM and Dark Energy (DE) is proposed. Two types of devices based on SQUID, in particular the SQUID-paramagnetic absorber and the SQUID-magnetostrictor systems, both suitable for investigations of above problems, are considered.

physics.gen-ph↗