Experimental results on evaporation waves

We address an experimental investigation of evaporation waves. They are obtained when a liquid contained in a vertical glass tube is suddenly depressurized from a high initial pressure down to the atmospheric one. After the release of pressure, the state of the liquid, which is at ambient pressure and the initial temperature, is well known to be metastable when the corresponding stable state is vapour. For moderately large evaporation rates (moderately large initial to ambient pressure ratios), the vapour-liquid interface ultimately evolves into an evaporation wave in which a highly corrugated front propagates downwards into the liquid with a well defined mean velocity. This mean velocity turns out to be a function of the ratio between the initial and the ambient pressures. In addition, attention to some new phenomena not previously reported is brought

Relativity of simultaneity in secondary school: an analysis based on the theory of the conceptual fields

In this paper, we present results about the conceptualization of the relativity of simultaneity and the operational invariants used by high school students. The Theory of Conceptual Fields is adopted to design, analyse and evaluate a didactic sequence to teach the basic aspects of the Theory of Special Relativity in secondary school. Only the situations related to the relativity of simultaneity are analysed here. An inductive categorization is constructed from 256 protocols generated in the implementations carried out in four 11th grade courses (15-16 years) (N = 128) in a public school of Colombia. The categorization identifies the resolutions of the students and the operative invariants that they use in each situation. The results indicate that the proposed situations would produce the emergence and awareness of the operational invariants linked to the relativity of Galileo, which would open the way to the conceptualization of the relativity of simultaneity in secondary school.Fil: Otero, Maria Rita. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Núcleo de Investigación en Educacion Ciencia y Tecnologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Arlego, Marcelo José Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentin

Teaching and learning optics in high school: from Fermat to Feynman

In this article, we analyze the basis of a proposal that allows teaching the notions of reflection, refraction, interference and diffraction from a unified perspective, using Fermat’s variational principle, recovered by Richard Feynman in his formulation of the paths sum for quantum mechanics. This allows reconsidering the notions of geometrical and physical optics, using the probabilistic and unified model of quantum mechanics by means of mathematical notions that are accessible to high school students.Fil: Otero, Maria Rita. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Núcleo de Investigación en Educacion Ciencia y Tecnologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Arlego, Marcelo José Fabián. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentin

Contact line depinning from sharp edges

With aim of finding mathematical criteria for contact line depinning from sharp corners, we have studied the equilibrium and stability of a semi-infinite planar liquid layer pinned at the vertex of a wedge. Equilibrium is compatible with a fan of apparent contact angles $\theta_0$ bracketed by the equilibrium contact angles of both flanks of the wedge, so the contact line could remain pinned if $\theta_0$ is within this fan. However, the analysis of the stability of these solutions, studied exploiting the variational structure of the problem through turning-point arguments, shows that the equilibrium becomes unstable at critical depinning advancing $\theta_0^a$ and receding $\theta_0^r$ contact angles, which are found as subcritical saddle-node bifurcations. Equilibrium is thus possible (stable) within the interval $\theta_0^a < \theta_0 <\theta_0^a$ but the contact line depins from the vertex beyond these critical angles if they occur within the equilibrium fan.Comment: 9 pages, 5 figure

(Proposta, análise e reformulação de uma sequência didática para o ensino da teoria da relatividade especial no Nível Médio

In this work, we design, implement and analyze a didactic sequence for the teaching of the basic topics of special relativity theory in high school. The sequence proposes a series of situations, specially designed to allow the emergence of the central aspects of special relativity. The conceptualization process is investigated from the point of view of the theory of conceptual fields of Vergnaud. By means of a careful analysis of classroom student productions we detect the key theorems-in-action they use, evidencing that most of conceptual errors are of pre-relativistic nature. This leads us to a reformulation of the sequence, which promotes the conceptualization of Galilean relativity and the principles of the special relativity. This previous step aims at bringing to students a firm basis to address the more complex aspects of the subject.Instituto de Física La PlataFacultad de Ingenierí

Teaching the basic concepts of the Special Relativity in the secondary school in the framework of the Theory of Conceptual Fields of Vergnaud

In this work, we investigate the conceptualization of the basic aspects of Special Relativity (SR) at secondary school level. We have conducted our research along the lines of the Theory of Conceptual Fields (TCF) proposed by Vergnaud (Vergnaud G., Infancia y Aprendizaje, 36 (2013) 131). The investigation consisted in the design, implementation and evaluation of a didactic sequence specially elaborated to conceptualize the basic aspects of SR. The proposal is composed by eight situations, complemented with a set of exercises. It was carried out in two classrooms with students of the last year of secondary level (17 years old, N = 43). The conceptualization was analyzed in a classroom context, where the selected situations are essential to promote the emergence of the relevant concepts.Facultad de Ciencias ExactasInstituto de Física La PlataFacultad de Ingenierí

Enseñanza del Cálculo Vectorial en la Universidad: propuesta de Recorridos de Estudio e Investigación

En este trabajo realizamos una propuesta para la enseñanza del Cálculo Vectorial en el contexto de una Facultad de Ingeniería mediante el dispositivo didáctico llamado Recorridos de Estudio e Investigación (REI). Este dispositivo ha sido propuesto por Chevallard en el marco de la Teoría Antropológica de lo Didáctico (TAD), que plantea una enseñanza bajo el paradigma de la pedagogía de la investigación y del cuestionamiento del mundo. Analizamos las condiciones que facilitarían y las que obstaculizarían la ecología del REI en esa institución e introducimos el modelo praxeológico de referencia. Finalmente presentamos una descripción de la implementación del REI y un análisis preliminar de las organizaciones matemáticas que surgieron en el mismo.In this work we elaborate a proposal for vector calculus teaching in the context of a Faculty of Engineering by means of the teaching device called Trajectories of Study and Research (TEI). This device has been introduced by Chevallard in the framework of Anthropological Theory of Didactics (ATD), which proposes a teaching under the paradigm of pedagogy of research and questioning the world. We analyze the conditions that facilitate and those that hamper TEI ecology in that institution and introduce the reference praxeological model. Finally we present a description of REI implementation and a preliminary analysis of mathematical organizations that emerged after its implementation.Fil: Costa, Viviana Angélica. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Núcleo de Investigación en Educacion Ciencia y Tecnologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arlego, Marcelo José Fabián. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Núcleo de Investigación en Educacion Ciencia y Tecnologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Otero, Maria Rita. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Núcleo de Investigación en Educacion Ciencia y Tecnologia; Argentin

Parcours d'études et de recherche en mathématiques et en physique au sein de deux groupes de formation initiale des enseignants

In this paper, we present results of an inquiry based teaching implementation carried out on a teacher training course in the University. The framework of the Anthropological Theory of Didactics (ATD) is adopted, and a co-disciplinary Study and Research Path (SRP) whose generative question requires studying physics and mathematics together is carried out by N=25 training teachers of Mathematics at University. Some conclusions concerning the conditions, restrictions and relevance of introducing the RSC in teachers training courses at the university are performed.Dans ce travail nous présentons des résultats d'un enseignement développé dans un cours de formation d’enseignants de mathématiques à l'Université. On adopte le cadre théorique de la Théorie Anthropologique du Didactique (TAD) pour développer un Parcours d'Étude et Recherche (PER) avec N=25 enseignants de Mathématiques en formation à l'université. La question génératrice demande l’étude conjointe des mathématiques et de la physique. Nous faisons quelques remarques liées aux conditions, restrictions et à l'importance des PER dans la formation des enseignants à l’université.Fil: Otero, Maria Rita. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Núcleo de Investigación en Educacion Ciencia y Tecnologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Llanos, Viviana Carolina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Núcleo de Investigación en Educacion Ciencia y Tecnologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arlego, Marcelo José Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentin

A proposal to teach light in a unified framework using the Feynman method

The goal of this proposal is to teach the basic aspects of light from the point of view of quantum mechanics at high school level. To this end, we have adapted Feynman´s Path Integral Method of Quantum Mechanics. This is a continuation of previous works where we considered the quantum behaviour of matter. The situations were to promote the conceptualization of the electron as a quantum system, the probabilistic function and the transition quantum-classic. Now, the goal is to build a new proposal to teach the behaviour of the light from an actual vision and from a unified model: the quantum mechanics, from the reconstruction of a reference that also uses the approach Path Integrals of Richard Feynman. It is adapted for secondary school students using vectors and sums, and it is inserted in a problems context about the light. Careful and accurate language is used, avoiding terms like photon or expressions likeparticles of light or wave-particle duality, because these ideas could present obstacles to understanding key aspects of quantum theory. This proposal is an alternative to avoid historical approaches commonly used so far and it is being implemented in two groups of students in secondary school (15-16 years old).Instituto de Física La Plat

A proposal to teach light in a unified framework using the Feynman method

The goal of this proposal is to teach the basic aspects of light from the point of view of quantum mechanics at high school level. To this end, we have adapted Feynman´s Path Integral Method of Quantum Mechanics. This is a continuation of previous works where we considered the quantum behaviour of matter. The situations were to promote the conceptualization of the electron as a quantum system, the probabilistic function and the transition quantum-classic. Now, the goal is to build a new proposal to teach the behaviour of the light from an actual vision and from a unified model: the quantum mechanics, from the reconstruction of a reference that also uses the approach Path Integrals of Richard Feynman. It is adapted for secondary school students using vectors and sums, and it is inserted in a problems context about the light. Careful and accurate language is used, avoiding terms like photon or expressions likeparticles of light or wave-particle duality, because these ideas could present obstacles to understanding key aspects of quantum theory. This proposal is an alternative to avoid historical approaches commonly used so far and it is being implemented in two groups of students in secondary school (15-16 years old).Instituto de Física La Plat