Scielo RSS <![CDATA[Revista Brasileira de Ensino de Física]]> http://www.scielo.br/rss.php?pid=1806-111720170004&lang=es vol. 39 num. 4 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[Astronomy Communication and Popularization in the Brazilian Amazonia: The Astronomy Nucleus of the Federal University of Pará]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172017000400301&lng=es&nrm=iso&tlng=es Abstract The Astronomy Nucleus of the Federal University of Pará is a science center located in the Brazilian Amazonia, dedicated to spread knowledge on Astronomy to the general public. Over the last ten years, this science center has promoted several activities, including astronomical observations, demonstrations with industrially manufactured and low cost material equipment, seminars, workshops, among others. We describe and discuss the role of the Astronomy Nucleus and other science centers dedicated to Astronomy communication and popularization in the Brazilian Amazonia. <![CDATA[Relativistic effects on uniformly accelerated observers]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172017000400401&lng=es&nrm=iso&tlng=es Neste trabalho apresentaremos uma introdução sobre o espaco-tempo de Rindler a partir de uma abordagem didática a fim de obtermos as equações de movimento que descrevem observadores uniformemente acelerados em um espaco-tempo plano. Em seguida, generalizaremos, descrevendo o movimento associado a um observador uniformemente acelerado no espaco-tempo em expansão de Friedmann-Lemaître-Robertson-Walker.<hr/>In this article we presented an introduction to Rindler spacetime from a didactic approach in order to get the motion equations describing uniformly accelerated observers in the smooth spacetime. Then, we will treat the motion of uniformely accelerated observer in Friedmann-Lemaîtrre-Robertson-Walker expanding spacetime. <![CDATA[A discussion on coefficient of restitution]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172017000400402&lng=es&nrm=iso&tlng=es Seja em escala atômica, seja em escala macroscópica, a quantidade de eventos de colisão em nosso cotidiano é considerável e, portanto, os esforços em estudos que aumentam nossa compreensão destas colisões são essenciais tanto para o ensino como para o desenvolvimento de futuras tecnologias. Em processos de colisão, o coeficiente de restituição está associado ao grau de elasticidade da colisão entre os corpos em questão e nos permite classificar as colisões como elásticas, inelásticas e super-elásticas. No entanto, não é habitual observar na literatura uma abordagem matemática ampla e detalhada para explicar, de forma didática, esta classificação, o que acarreta o surgimento de dúvidas sobre o coeficiente de restituição. Nesse sentido, desenvolvemos neste artigo demonstrações detalhadas para cada caso, além de apresentar exemplos de colisões endoérgicas e colisões exoérgicas.<hr/>The amount of collision events in our daily lives, whether at the atomic scale or at macroscopic scale is considerable and therefore efforts in studies that increase our understanding of these collisions are essential both for teaching as for the development of future technologies. In collision processes, the coefficient of restitution is associated with the degree of elasticity of the collision between the bodies in concerned and allows us to classify the collision as elastic, inelastic and super-elastic. However, it is unusual to see in literature a comprehensive and detailed mathematical approach to explain, in a didactic way, this classification, which leads to the emergence of doubts about the coefficient of restitution. In accordance with this context, we develop in this article, detailed and appropriate demonstrations for each case, in addition to present examples of endoérgicas and exoérgicas collisions. <![CDATA[Development of a computational instrument using a lagrangian particle method for physics teaching in the areas of fluid dynamics and transport phenomena]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172017000400501&lng=es&nrm=iso&tlng=es Abstract Particle methods are an alternative to the traditional mesh Eulerian methods for solution of fluid dynamics and transport phenomena problems. The Lagrangian Meshless Smoothed Particle Hydrodynamics (SPH) method presents advantages compared to mesh methods as a better visualisation of the spatio-temporal evolution of the flow (and the fluid properties), and a lower computational cost in the study of complex geometries with topological changes, or free surfaces. A computer code has been written for serial computation using FORTRAN Programming Language. Three classical physical problems have been simulated: diffusion in a flat plate, still fluid within an immobile reservoir and dam breaking. In code validation, numerical results obtained showed a good agreement with the analytical and experimental results reported in the literature. The numerical code developed and presented in this work is a valuable tool for the teaching of Physics. <![CDATA[A review of Black Holes: the BBC Reith Lectures]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172017000400901&lng=es&nrm=iso&tlng=es Apresenta-se uma resenha crítica do livro Buracos negros: palestras da BBC Reith Lectures, de autoria de Stephen Hawking. O livro é a transcrição de duas palestras que o autor ministrou em 2016 para a BBC Radio 4 e pode ser entendido uma introdução sobre o tema, adequada para leigos e estudantes de ensino médio.<hr/>A critical review of Stephen Hawking's Black Holes: the BBC Reith Lectures is presented. The book is a transcript of two lectures that the author gave in 2016 to BBC Radio 4 and can be understood as an introduction on the subject, suitable for laymen and high school students.