cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14326517
title: Alternative methodology of porous media bulk density measurement in didactic physics laboratories

description: When the physical quality of porous media such as soil is studied one of the properties of great importance is its bulk density, ρs. Measurements of ρs have great relevance due to its influence in other porous system properties (e.g. porosity, volumetric water content, water storage, etc.). In this paper is proposed an alternative methodology of ρs measurement named vacuum-sealed method. Samples coating, contrary to the traditional methods such as the paraffin-coated, was carried out using a plastic packaging followed by the sample internal air evacuation through a vacuum pump device. The determination of the clod samples ρs by the paraffin-coated method was utilized as a reference. The obtained results showed that compared to the paraffin-coated method, the average ρs measured by the vacuum-sealed method presented underestimated values considering all the soils analyzed. The proposed method is faster and has greater coating reliability than the traditional method with the additional advantage of sample reuse for new measurements. The new method can also be easily implemented in teaching physics laboratories in high school grade and bachelor’s, engineering, and environmental science courses. As a method that requires minimal sample preparation, easy to implement, and fast, it becomes ideal for the study not only of ρs but also to the discussion of concepts involved in its measurement such as mass, volume, weight, apparent weight and buoyancy force.
DOI: 10.6084/m9.figshare.14326517.v1
title: Alternative methodology of porous media bulk density measurement in didactic physics laboratories

description: When the physical quality of porous media such as soil is studied one of the properties of great importance is its bulk density, ρs. Measurements of ρs have great relevance due to its influence in other porous system properties (e.g. porosity, volumetric water content, water storage, etc.). In this paper is proposed an alternative methodology of ρs measurement named vacuum-sealed method. Samples coating, contrary to the traditional methods such as the paraffin-coated, was carried out using a plastic packaging followed by the sample internal air evacuation through a vacuum pump device. The determination of the clod samples ρs by the paraffin-coated method was utilized as a reference. The obtained results showed that compared to the paraffin-coated method, the average ρs measured by the vacuum-sealed method presented underestimated values considering all the soils analyzed. The proposed method is faster and has greater coating reliability than the traditional method with the additional advantage of sample reuse for new measurements. The new method can also be easily implemented in teaching physics laboratories in high school grade and bachelor’s, engineering, and environmental science courses. As a method that requires minimal sample preparation, easy to implement, and fast, it becomes ideal for the study not only of ρs but also to the discussion of concepts involved in its measurement such as mass, volume, weight, apparent weight and buoyancy force.
DOI: 10.6084/m9.figshare.14326519
title: Solid propellant model rocket: theoretical aspects and experimental proposals for teaching physics

description: In this work, a solid propellant model rocket was built as a proposal for a playful activity, in which students can learn physics, mathematics and computer simulation in practice. A whole theoretical approach was carried out on physical quantities that appear in the model rocket and thermodynamic equation. The rate of exhaustion and the variation in mass with time which appear in the impulse formula of the model rocket, could be determined with the equation of altitude as a function of time using a digital altimeter. These quantities were compared with theoretical values comparing experience and theory. In the construction part, all steps were shown, from the preparation of the fuel, to the model rocket ready to launch on a base. Here the student has the opportunity to understand how a real rocket works with solid propellant, since the difference between this and a model rocket is only the scale.
DOI: 10.6084/m9.figshare.14326519.v1
title: Solid propellant model rocket: theoretical aspects and experimental proposals for teaching physics

description: In this work, a solid propellant model rocket was built as a proposal for a playful activity, in which students can learn physics, mathematics and computer simulation in practice. A whole theoretical approach was carried out on physical quantities that appear in the model rocket and thermodynamic equation. The rate of exhaustion and the variation in mass with time which appear in the impulse formula of the model rocket, could be determined with the equation of altitude as a function of time using a digital altimeter. These quantities were compared with theoretical values comparing experience and theory. In the construction part, all steps were shown, from the preparation of the fuel, to the model rocket ready to launch on a base. Here the student has the opportunity to understand how a real rocket works with solid propellant, since the difference between this and a model rocket is only the scale.
DOI: 10.6084/m9.figshare.14326520.v1
title: Simulation in Easy Java for the Poynting field of a circular circuit

description: The simulations of physical phenomena are translated into a place within the techniques used to innovate the traditional teaching of Physics. In this paper, we describe how to make an Easy Java simulation for the Poynting field around a circular circuit. Through a mathematical analysis we can find the vector field for the Poynting vector. Once obtained, we can develop a graphical way to represent a simulation for easy assimilation in university education. The advantage of creating a simulation is that the student can use the ease of calculation provided by the computer to visualize and understand the Poynting field of an electric circular circuit, without resorting to a traditional lab real experiment.
DOI: 10.6084/m9.figshare.14326520
title: Simulation in Easy Java for the Poynting field of a circular circuit

description: The simulations of physical phenomena are translated into a place within the techniques used to innovate the traditional teaching of Physics. In this paper, we describe how to make an Easy Java simulation for the Poynting field around a circular circuit. Through a mathematical analysis we can find the vector field for the Poynting vector. Once obtained, we can develop a graphical way to represent a simulation for easy assimilation in university education. The advantage of creating a simulation is that the student can use the ease of calculation provided by the computer to visualize and understand the Poynting field of an electric circular circuit, without resorting to a traditional lab real experiment.
DOI: 10.6084/m9.figshare.14268889
title: Quantum Theory of Atoms in Molecules

description: Abstract The proposition of a modern atomic dimensionality should be laureate to the pioneering spirit of the theoretician in physics and chemistry, Richard Bader. By taking into account the electronic-density as a pure and physical variable, Bader has formulated a mathematical protocol for modeling the charge density fluxes on the molecular surfaces. To this end, he also assumed the atomic environment as being an open space suitable for exchange charge and momentum with the neighbors around it. The integration of the molecular surface is ruled by the virial theorem embodied by the contributions of the kinetic and potential energy densities, wherein, both of them are represented by the Laplacian field of the electronic density.
DOI: 10.6084/m9.figshare.14268889.v1
title: Quantum Theory of Atoms in Molecules

description: Abstract The proposition of a modern atomic dimensionality should be laureate to the pioneering spirit of the theoretician in physics and chemistry, Richard Bader. By taking into account the electronic-density as a pure and physical variable, Bader has formulated a mathematical protocol for modeling the charge density fluxes on the molecular surfaces. To this end, he also assumed the atomic environment as being an open space suitable for exchange charge and momentum with the neighbors around it. The integration of the molecular surface is ruled by the virial theorem embodied by the contributions of the kinetic and potential energy densities, wherein, both of them are represented by the Laplacian field of the electronic density.
DOI: 10.6084/m9.figshare.14326522
title: The history of the problem of collisions in the seventeenth century's physics before Newton

description: Abstract This paper provides a historical overview of the treatment of the problem of collisions throughout the 17th century, up to the great mechanical synthesis of Newton. At first we present the pioneering approaches of Thomas Harriot and Isaac Beeckman. We then proceed to Descartes's attempt to solve the problem by briefly presenting his philosophical foundations and the systematic construction he sought, which ultimately turned out to be wrong. We then proceed to the analysis of the formulations proposed by Christopher Wren, John Wallis and Christiaan Huygens, all of them achieving correct results, albeit with restricted application. We seek to highlight the particularities of each of these elaborations, emphasizing the pioneering introduction in physics of the use of negative numbers in determining the direction of motion, carried out by Wren and Wallis, and the extremely systemic character of Huygens's mechanical thinking, building his solution from the application of fundamental physical principles, some already known and others outlined by him.
DOI: 10.6084/m9.figshare.14326522.v1
title: The history of the problem of collisions in the seventeenth century's physics before Newton

description: Abstract This paper provides a historical overview of the treatment of the problem of collisions throughout the 17th century, up to the great mechanical synthesis of Newton. At first we present the pioneering approaches of Thomas Harriot and Isaac Beeckman. We then proceed to Descartes's attempt to solve the problem by briefly presenting his philosophical foundations and the systematic construction he sought, which ultimately turned out to be wrong. We then proceed to the analysis of the formulations proposed by Christopher Wren, John Wallis and Christiaan Huygens, all of them achieving correct results, albeit with restricted application. We seek to highlight the particularities of each of these elaborations, emphasizing the pioneering introduction in physics of the use of negative numbers in determining the direction of motion, carried out by Wren and Wallis, and the extremely systemic character of Huygens's mechanical thinking, building his solution from the application of fundamental physical principles, some already known and others outlined by him.
DOI: 10.6084/m9.figshare.14269556
title: Gerhard Jacob, the scientist and academic manager

description: In its 60th year of foundation, the IF-UFRGS no longer has its three main creators. Theodor Maris passed away on August 20, 2010, Darcy Dillenburg on January 15, 2015 and Gerhard Jacob on October 25, 2018. Of the three, Gerhard was the one with whom I had the closest personal proximity. I digitalized part of his documentary collection, and we had planned to write a collaborative article from his reminiscences, a text of 80 pages he had given me to read, comment, and evaluate what destination would be given to it. Circumstances of our professional lives prevented the project from being executed on time. In the present work, the biographical profile of prof. Gerhard will be presented from relevant information contained in that memory, information collected from the IF-UFRGS files and from the professor’s personal files, as well as information extracted from an interview he gave to the present author in 2015. A brief analysis of the scientific contribution of prof. Gerhard and his role as manager at UFRGS and various external institutions, especially CNPq, of which he was a member of the Deliberative Council and its chairman.
DOI: 10.6084/m9.figshare.14269556.v1
title: Gerhard Jacob, the scientist and academic manager

description: In its 60th year of foundation, the IF-UFRGS no longer has its three main creators. Theodor Maris passed away on August 20, 2010, Darcy Dillenburg on January 15, 2015 and Gerhard Jacob on October 25, 2018. Of the three, Gerhard was the one with whom I had the closest personal proximity. I digitalized part of his documentary collection, and we had planned to write a collaborative article from his reminiscences, a text of 80 pages he had given me to read, comment, and evaluate what destination would be given to it. Circumstances of our professional lives prevented the project from being executed on time. In the present work, the biographical profile of prof. Gerhard will be presented from relevant information contained in that memory, information collected from the IF-UFRGS files and from the professor’s personal files, as well as information extracted from an interview he gave to the present author in 2015. A brief analysis of the scientific contribution of prof. Gerhard and his role as manager at UFRGS and various external institutions, especially CNPq, of which he was a member of the Deliberative Council and its chairman.
DOI: 10.6084/m9.figshare.14326523
title: A third way between Newton and Leibniz would be viable: Boscovich's Natural Philosophy

description: Abstract This article explores the main aspects of the Natural philosophy of the Jesuit Ruggero Giuseppe Boscovich and tries to stress the consistency between the reflections he fostered for the elaboration of his great work, Theoria Philosophiae Naturalis, and the eighteenth-century discussion on the opposition between the perspectives of Isaac Newton and Gottfried Leibniz, an opposition which continued even after their deaths.
DOI: 10.6084/m9.figshare.14326523.v1
title: A third way between Newton and Leibniz would be viable: Boscovich's Natural Philosophy

description: Abstract This article explores the main aspects of the Natural philosophy of the Jesuit Ruggero Giuseppe Boscovich and tries to stress the consistency between the reflections he fostered for the elaboration of his great work, Theoria Philosophiae Naturalis, and the eighteenth-century discussion on the opposition between the perspectives of Isaac Newton and Gottfried Leibniz, an opposition which continued even after their deaths.
DOI: 10.6084/m9.figshare.14326528
title: César Lattes and the techniques of production and detection of mesons: scientific practice as historical object

description: The main goal of this article is to present the scientific investigations of the Brazilian physicist César Lattes in the 1940s, which lead him to produce, capture and identify pi and mu mesons. Using unpublished primary sources hold by archives in Brazil and the United States, as the syllabus of the courses Lattes took and the notebooks from the Lawrence Radiation Laboratory, we analyze the experimental skills he had developed and improved. He has combined scientific instruments from different institutions using in his experiments theories that were recently appearing to reach his goals. Thus, we take Lattes’ scientific practice as a historical object, focusing on his strategies of detection which have conditioned his choices of the laboratories to develop his work.
DOI: 10.6084/m9.figshare.14326528.v1
title: César Lattes and the techniques of production and detection of mesons: scientific practice as historical object

description: The main goal of this article is to present the scientific investigations of the Brazilian physicist César Lattes in the 1940s, which lead him to produce, capture and identify pi and mu mesons. Using unpublished primary sources hold by archives in Brazil and the United States, as the syllabus of the courses Lattes took and the notebooks from the Lawrence Radiation Laboratory, we analyze the experimental skills he had developed and improved. He has combined scientific instruments from different institutions using in his experiments theories that were recently appearing to reach his goals. Thus, we take Lattes’ scientific practice as a historical object, focusing on his strategies of detection which have conditioned his choices of the laboratories to develop his work.
DOI: 10.6084/m9.figshare.14326529.v1
title: About the Teaching of Plane Motion of Rigid Bodies

description: The study of the motion of a rigid body on a plane (RBP motion) is usually one of the most challenging topics that students face in introductory physics courses. In this paper, we discuss a couple of problems which are typically used in basic physics courses, in order to highlight some aspects related to RBP motion which are not usually well understood by physics students. The first problem is a pendulum composed of a rod and disk. The angular frequency of the pendulum is calculated in two situations: disk fixed to the rod and disk free to spin. A detailed explanation of the change in the angular frequency from one case to another is given. The second problem is a ladder which slides touching a frictionless surface. We use this problem to highlight the fact that the contact forces applied by the surface perform translational and rotational work despite that the total mechanical energy of the ladder is conserved.
DOI: 10.6084/m9.figshare.14326529
title: About the Teaching of Plane Motion of Rigid Bodies

description: The study of the motion of a rigid body on a plane (RBP motion) is usually one of the most challenging topics that students face in introductory physics courses. In this paper, we discuss a couple of problems which are typically used in basic physics courses, in order to highlight some aspects related to RBP motion which are not usually well understood by physics students. The first problem is a pendulum composed of a rod and disk. The angular frequency of the pendulum is calculated in two situations: disk fixed to the rod and disk free to spin. A detailed explanation of the change in the angular frequency from one case to another is given. The second problem is a ladder which slides touching a frictionless surface. We use this problem to highlight the fact that the contact forces applied by the surface perform translational and rotational work despite that the total mechanical energy of the ladder is conserved.
DOI: 10.6084/m9.figshare.14326531
title: The Crookes’s Radiometer is a light vane

description: One of the most important experiments of the 19th century makes a connection between electromagnetism and mechanics in a direct way. In the so called “Crooke’s Radiometer” the light, pulling vanes, surprises us giving the immediate perception of its energy. The public perceives that is the black side which receives the greater action. The school and the universitarie’s students, they try to understand why it is so, but doubts remain. In this article we make a review of those doubts at three levels: school, graduation and post-graduation. The usual thinking employs electromagnetism, thermodynamics, but we do not know any article which who may had included friction on the analysis. We show here the influence of friction by performing a simple experiment.
DOI: 10.6084/m9.figshare.14326531.v1
title: The Crookes’s Radiometer is a light vane

description: One of the most important experiments of the 19th century makes a connection between electromagnetism and mechanics in a direct way. In the so called “Crooke’s Radiometer” the light, pulling vanes, surprises us giving the immediate perception of its energy. The public perceives that is the black side which receives the greater action. The school and the universitarie’s students, they try to understand why it is so, but doubts remain. In this article we make a review of those doubts at three levels: school, graduation and post-graduation. The usual thinking employs electromagnetism, thermodynamics, but we do not know any article which who may had included friction on the analysis. We show here the influence of friction by performing a simple experiment.
DOI: 10.6084/m9.figshare.14326532.v1
title: Black holes shadows: unveiling the physics behind the image of M87

description: In this article we analyze the shadows of spinning Kerr black holes and their connection with the first image of a black hole obtained by the international collaboration Event Horizon Telescope. We obtain analytically the shadow of a rotating black hole from the spherical photon orbits. We also use the method known as backwards ray-tracing to illustrate the visual perception of an observer in the presence of a spinning black hole with and without an accretion disk.
DOI: 10.6084/m9.figshare.14326534
title: Random Rotations

description: Rotations are among the simplest and most important of linear operations, and the group of rotations is a fundamental structure both for physics and geometry. In the article, we present an introductory discussion about random rotations, which can be seen as an example from the more general theory of random operators or random matrices, area which finds countless applications. We discuss the structure of the orthogonal group. an algorithm for generating random rotations and results for the probability distributions of matrix elements and eigenvalues.
DOI: 10.6084/m9.figshare.14326534.v1
title: Random Rotations

description: Rotations are among the simplest and most important of linear operations, and the group of rotations is a fundamental structure both for physics and geometry. In the article, we present an introductory discussion about random rotations, which can be seen as an example from the more general theory of random operators or random matrices, area which finds countless applications. We discuss the structure of the orthogonal group. an algorithm for generating random rotations and results for the probability distributions of matrix elements and eigenvalues.
DOI: 10.6084/m9.figshare.14326532
title: Black holes shadows: unveiling the physics behind the image of M87

description: In this article we analyze the shadows of spinning Kerr black holes and their connection with the first image of a black hole obtained by the international collaboration Event Horizon Telescope. We obtain analytically the shadow of a rotating black hole from the spherical photon orbits. We also use the method known as backwards ray-tracing to illustrate the visual perception of an observer in the presence of a spinning black hole with and without an accretion disk.
DOI: 10.6084/m9.figshare.14326537
title: Chua’s oscillator: an introductory approach to chaos theory

description: The purpose of this article is to build an introductory approach to chaos theory from the Chua’ oscillator for students of mathematics, physics and engineering. The Chua’ circuit is one of the simplest dynamic systems that produce irregular behavior. Despite its simplicity, this oscillating circuit is a very useful device for studying basic principles of chaos theory. This study begins with the definition of equilibrium points, this is done in a graphic and analytical way. The analysis of the stationary solution of differential equations system allows to show the occurrence of pitchfork bifurcation. The eigenvalues are calculated and the trajectories of the Chua’ oscillator are analyzed, then the occurrence of Hopf bifurcation is demonstrated. Period-doubling cascade are observed using phase portrait and orbit diagram. Finally, sensitivity to initial conditions is studied by calculating Lyapunov exponents.