Sacándole más jugo al problema de la corona. Primera parte: el tratamiento conceptual

En este trabajo se discuten de forma crítica algunas formulaciones y formas de resolución del problema de la corona de Arquímedes, analizando cuáles son más apropiadas para los alumnos de secundaria. Aunque no se sabe con certeza cómo el propio Arquímedes abordó el problema de la corona, es posible reflexionar acerca de cuáles eran las posibles vías de solución acorde con el estado de conocimiento de física y matemática en la época de Arquímedes. Tal reflexión en el aula daría a los estudiantes una oportunidad de ver cómo se podrían aplicar los conceptos de densidad y de fuerza de empuje para solucionar el mismo.Palabras clave: Corona de Arquímedes, densidad, fuerza de empuje, resolución de problemas.Getting the best out of to the problem of the crown. First part: the conceptual treatmentIn this paper, some formulations and ways of solving the problem of the Archimedes' crown are discussed in a critical way, analyzing which ones are more appropriate for secondary students. Although it is not known with certainty how Archimedes himself approached the problem of the crown, it is possible to reflect on which were possible ways of solution in agreement with the state of knowledge of physics and mathematics in the time of Archimedes. Such reflection in the classroom would give students an opportunity to see how the concepts of density and pushing force could be applied to solve it.Keywords: Archimedes crown, density, thrust force, problem solving

Sacándole más jugo al problema de la corona. Segunda parte: el tratamiento cuantitativo

En este trabajo se discuten de forma crítica algunas formulaciones y formas de resolución del problema de la corona de Arquímedes, analizando cuáles son más apropiadas para los alumnos de secundaria. Aunque no se sabe con certeza cómo el propio Arquímedes abordó el problema de la corona, es posible reflexionar acerca de cuáles fueron las posibles vías de solución acordes con el estado de conocimiento de física y matemática en la época de Arquímedes. Tal reflexión en el aula daría a los estudiantes una oportunidad de ver cómo se podrían aplicar los conceptos de densidad y de fuerza de empuje para solucionar el mismo.Palabras clave: Corona de Arquímedes, densidad, fuerza de empuje, resolución de problemas.Getting the best out of to the problem of the crown. Second part: the quantitative treatmentIn this paper, some formulations and ways of solving the problem of the Archimedes' crown are discussed in a critical way, analyzing which ones are more appropriate for secondary students. Although it is not known with certainty how Archimedes himself approached the problem of the crown, it is possible to reflect on which were possible ways of solution in agreement with the state of physical and mathematical knowledge in the time of Archimedes. Such reflection in the classroom would give students a chance to see how the concepts of density and pushing force could be applied to solve it.Keywords: Archimedean crown, density, thrust force, problem solving

XIII Taller Internacional sobre Enseñanza de la Física

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Developing critical analysis of explanations in physics teachers: Which direction to take?

International audienc

Electrostatic Deformation of Liquid Surfaces by a Charged Rod and a Van de Graaff Generator

Authors of physics textbooks frequently use the deflection of a thin, vertically falling water jet by a charged balloon, 1–3 comb, 4–6 or rod 7–9 as a visually appealing and conceptually relevant example of electrostatic attraction. Nevertheless, no attempts are made to explore whether these charged bodies could cause visible deformation of a horizontal water surface. That being so, we were quite surprised when we discovered that a 19th-century French book 10 contained a drawing showing an appreciable deformation of an oil surface caused by a charged rod. When we initially tried to recreate this electrostatics demonstration, we didn't succeed in reproducing the effect with a charged rod. Despite the initial unsuccessful try, we were not discouraged and we modified the demonstration a little bit, finding that it was possible to cause visible deformations of different liquid surfaces by using a Van de Graaff generator, as we will explain later.The work on this article was started during the visit of the first author to the Universitat d'Alacant (Spain), planned within the research project Active Physics Learning Online, supported by the CONACyT (Mexico). Financial support from the Centro de Estudios Iberoamericanos Mario Benedetti