Vol. 19 No. 1 Jan-Jun (2022): Revista Mexicana de Física E

It is shown how through the entropy production rate a natural unification between the formalism of classical thermodynamics and chemical kinetics is achieved. It is also shown how the entropy production rate represents an alternative way to the sensitivity analysis method in order to determine the fundamental steps in a reaction mechanism.

The influence of the force of the quadratic resistance of the medium on the change in some interesting characteristics of the motion of the projectile, which take place when the projectile moves in vacuum, is investigated. Loci are constructed numerically (and partly analytically) that ensures maximization of the arc length of the projectile trajectory and a non-decreasing of the length of the radius-vector. As examples, the motion of a baseball, a tennis ball and a badminton shuttlecock is studied.

This article provides undergraduates a useful tool for a better understanding of the time delay eect on a electronic circuit. The time delay eect is analyzed on this paper in a rst order dierential equation. This linear time delay is associated with the amplitude of a first-order dierential equation and is responsible of three responses: one of the responses is an dierential equation type in first-order without delay, another one of the responses is a dierential equation type in second-order and nally we have the response of a harmonic oscillator.The proposed circuit is an emulator that develop the three different responses mentioned above. Simulink-Matlab software was used to implement the time delay and simulate the dierential equation. This simulation results coincide with the theoretical results. In the same manner, the experimental results match those of the theory. The electronical circuits suggested consist of three blocks: an integrator block, a phase shift block and a gain block. The electrical circuit is composed of resistors, capacitors and operational ampliers.

En este trabajo se replicó un método basado en el teorema de Vergnaud sobre la conceptualización del campo eléctrico con cálculo integral realizado en una universidad privada de la ciudad de Guayaquil. El objetivo  de este estudio es relacionar y conectar la interacción que existe entre el dominio conceptual – epistemológico (Saber comprender) con el hacer del dominio metodológico (Saber hacer) con el propósito de ampliar y profundizar el concepto mediante la experimentación a través de un material instruccional en las clases virtuales (Teoría de Gagné). Nuestro trabajo se fundamenta en la investigación acción con un enfoque explicativo, ya que desde la óptica de la práctica pedagógica pretendemos dar respuesta a los problemas de conceptualización sobre las variables que participan en el campo eléctrico. El diseño del estudio es experimental se trabajó con grupos intactos, uno de control (Gc) y otro experimental (Ge).  Los resultados indican que el grupo experimental desarrolló una mejor conceptualización en los contenidos de campo eléctrico con cálculo integral a diferencia del grupo de control que recibió una instrucción tradicional.

Notions of Electromagnetism and Special Theory of Relativity (STR) require important mathematical knowledge applied to theoretical physics. Recognizing pedagogical difficulties in the teaching of theoretical physics, the Theory of Didactical Situations (TDS), which consists of a set of practices that aim to contribute to the improvement of mathematics teaching. In this context, the present work is motivated to present a set of practices based on TDS with a focus on teaching Electromagnetism and STR, where problems that require an understanding of the transformations of Galileo and Lorentz. Specifically, the didactic situation is constructed by means of four problem proposals, while in the adidatic situation, the student is invited to understand the roles of these transformations in the study of these problems. Ultimately, the relevance of the educator in the institutionalization situation is reinforced, a moment when it must be clarified how all mathematical relations are strongly related to physical principles.

A time method to approximate the solution of a class of nonlinear Schrödinger systems, which preserves the power of each component and the Hamiltonian of the system exactly, is presented. Spatial discretizations based on fourth- and sixth-order explicit and compact finite difference formulas are considered, however higher order formulas could also be used. The time
advancing technique is based on a modification of a conservative Crank-Nicolson scheme, which is applied sequentially to each of the components of the vector field. Conservation of discrete invariants and order of convergence of the method are validated by means of a series of numerical experiments using different nonlinear potentials.

 

This paper provided physics principles and a method to heating up a lantern with a tealight candle, so it reaches 2.5 m within the shortest time. The experiments aimed to determine optimal parameters in filling paper lanterns with hot air and the ideal shape of lanterns that would travel most quickly in a vertical direction. Hot air from burning a 28-wick candle was directed through a heat transfer system to fill the lanterns. The small ellipsoid lantern required the shortest time. This problem is suitable as a platform for STEM education approach on topics of convection, buoyancy and drag force.

Physics learning during the Covid-19 pandemic must still be done so that students can still get physics intake. This phenomenological research aims to explore physics teacher strategies in conducting traditional game-based learning in senior high schools during the Covid-19 pandemic. The research data was collected through in-depth interviews with 10 physics teachers from five senior high schools in Yogyakarta. The ten participants were taken using the purposive sampling technique. The data analysis used analytic reduction which started with identifying important statements from the interview results, determining the core theme, and interpreting the physics learning strategy essence. The research results found that traditional game-based physics learning was carried out using contextual, inquiry, project, and problem-based learning models. The physics material is integrated into traditional games which include tulup, benthik, bekelan, sulamanda, egrang, sekongan, jeblugan, and gobak sodor. Physics learning evaluation is carried out by assessing assignments, performance, presentations, tests, and the results of making students' traditional games. Traditional game-based physics learning is done through distance learning applications such as Zoom, Google Meet, Google Classroom, Google Mail, and WhatsApp. Supporting factors for learning physics based on traditional games include efficient learning, learning can be done anywhere, and students can explore their abilities widely. Inhibiting factors for learning physics based on traditional games include unstable internet networks, students’ different abilities, and never done distance learning. The physics teacher’s competence, the student’s abilities, and the facilities availability are the main factors in determining the learning physics success based on traditional games during the Covid-19 pandemic.

This study aims to find equations and simulations that satisfy the characteristics of graphene’s energy dispersion and identify misconceptions that may occur. Here we give students nine articles about graphene’s dispersion energy. They were asked to identify the equations, parameters, and software used in each of the articles. The assignment was then to make the distribution of the data in a spreadsheet. The parameters used were the lattice constant of 2.46 Å, the range of the k wave function for the x and y axes of -2πa to 2πa, and the interval for each range of 0.1. Each equation is divided into two parts, E(+) and E(-). The analysis was carried out by making a slice in the middle of the x and y axes, as well as the main and off-diagonals. Graphene has Dirac points where the band gap is zero. This means that there is no distance or very small distance between the valence and conduction bands. From this activity, it can be concluded that Rozhkov (2016) has the equations and simulations that best satisfy graphene’s dispersion energy. Misconceptions occur in almost all existing equations and simulations.

The aim of this study is to analyze the ability of students to solve the problems of linear motion kinematics expressed in symbolic and numeric representation. Research was survey with cross-sectional design. Research subjects included 26 first year undergraduate students in physics at one of the State Universities in Malang which was consisted of 10 men and 16 women. The research instrument was open-ended test of linear motion kinematics problems expressed in symbolic and numeric representations with a reability of 0,807 The research data were analyzed using descriptive and non-parametric inferential statistics. The results showed that the ability of students to solve linear motion kinematics problems in both symbolic and numeric representation was medium. Students had difficulty solving physical problems in both symbolic and numeric representations. It was also found that the problems of linear motion kinematics in symbolic representations were more difficult for students to solve than numeric representations. The study suggested further research to explore the causes of student difficulties more authentically, e.g. by interviewing or thinking aloud.

In this article we explain in a new light two fundamental concepts ofquantum optics, the quantum beam splitter and the quantum interferometer, in termsof two state quantum wave functions. This method is consistent with the concept ofentanglement, and hence the algebra needed to describe them is reduced to additionsand products of the components of the quantum states. Furthermore, under thepremises of this method it is possible to study quantum states of greater complexity,like those arising from the addition and products of single photon states.

The Grad-Shafranov equation, often written in cylindrical coordinates, is an elliptic partial differential equation in two dimensions. It describes magnetohydrodynamic equilibria in axisymmetric toroidal plasmas, such as tokamaks, and yields the poloidal magnetic flux function, which is related to the azimuthal component of the vector potential for the magnetic field produced by a circular (toroidal) current density. The Green function for the differential operator can be obtained from the vector potential for the magnetic field of a circular current loop, which is a typical problem in magnetostatics. The purpose of the paper is to collect results scattered in electrodynamics and plasma physics textbooks for the benefit of students in the field, as well as attracting the attention of a wider audience, in the context of electrodynamics and partial differential equations.

A false positive in science is an announced discovery and then contested; the history of false positives illustrates the scientific process and the culture in which it is immersed. In the announcement of a false discovery, statistical fluctuations such as systematic errors of the experiments, the ambition of scientists, and the expectations and hopes of the research communities play a role, as well as practices and standards of the review process. On the way to building a scientific consensus there are obstacles of both social character and methodological nature. In the particular case of mathematics we have the case of the failed test, where a logical or conceptual error leads to the announcement of a correct result, which is reached by means of an erroneous argument. In this work, the history of failed demonstrations is discussed in mathematics such as the case of Vladimir Voevodsky, the controversy over the Mpemba effect, the diphoton excess fiasco at 750 GeV in the Large Hadron Collider, and the case of scientific dishonesty of Jan Hendrik Schon.