We show that at the onset of convection, the acceleration of a confined granular material is not necessarily equal to that of its vibrated container. Convection happens when the material is able to counter the downward gravitational pull... more
We show that at the onset of convection, the acceleration of a confined granular material is not necessarily
equal to that of its vibrated container. Convection happens when the material is able to counter the
downward gravitational pull and accelerates at a rate that is equal to the gravitational acceleration g.
We modify the Inelastic Bouncing Ball Model and incorporate the transmissibility parameter Tr which
measures the efficiency that the external force driving the container is transmitted to the material itself.
For a specified Tr value, the material is represented by an inelastic bouncing ball with a time-of-flight
T (Γ ; Tr) where Γ = A0ω
2
/g, is the dimensionless container acceleration, and A0 and ω are the driving
amplitude and angular frequency, respectively. For a given Γ -range, the T (Γ ; Tr) curve provides the
bifurcation diagram of the perturbed material and a family of bifurcation diagrams is generated for a
set of Tr values. We illustrate that Tr
is useful in rationalizing experimental results produced by confined
granular materials that is subjected to a range of applied force magnitudes. For the same physical set-up,
the force transmission efficiency from the container to the grains may not remain constant as the force
strength is varied. The efficiency is also affected by the presence or absence of air in the vibrated container.
Research Interests:
Research Interests:
The state of physics education and research in Africa have been discussed in several conferences. The proposals that are generated by these conferences advocate structural changes in higher education, North-South institutional linkages,... more
The state of physics education and research in Africa have been discussed in several conferences. The proposals that are  generated by these conferences advocate structural changes in higher education, North-South institutional linkages, mobilization of the African Diaspora and funding. In this presentation we will review the organization setting for physics education and research in Africa and the role of the emerging African Physical Society (AfPS) in shaping the Physics Enterprise in Africa, A recent article by James Lamout (Financial Times, August 2, 2001) indicates that emigration from South Africa alone costs $8.9 billion in lost human resources. The article also stated that every year 23,000 graduates leave Africa for opportunities overseas, mainly in Europe, leaving only 20,000 scientists and engineers serving over 600 million people. The International Organization for Migration states that the brain drain of highly skilled professionals from Africa is making economic growth and poverty alleviation impossible across the continent.  Specific to physics we focus on a possible networking mechanism where the African Diaspora their colleagues will play a major role in addressing the financial and human resources needs of higher education in Africa, in particular physics
Research Interests:
Research Interests:
Research Interests:
Complied Experiments in Modern Physics
Research Interests:
The objective of this paper is to provide some theoretical elements that contribute to the elucidation of questions about the tires, indicating the potential of the subject problematizations. We discourse along the text on the historical... more
The objective of this paper is to provide some theoretical elements that contribute to the elucidation of questions about the tires, indicating the potential of the subject problematizations. We discourse along the text on the historical evolution of the tire, as well as on the necessary basic Physics concepts to understand them. It is believed that this discussion, besides elucidating many everyday questions about the tires, it can be used as a reference for teachers, since, surprisingly, the subject of tires is absent in Physics textbooks of High School and University.
Research Interests:
Research Interests:
This paper reflects on the difficulties students have in understanding, designing and constructing electrical circuits through an analysis of errors they have made in drawing wiring and circuit diagrams. Prior to wiring a model house, a... more
This paper reflects on the difficulties students have in understanding, designing and constructing electrical circuits through an analysis of errors they have made in drawing wiring and circuit diagrams. Prior to wiring a model house, a sample of 114 primary school teacher trainees were taken through a programme of instruction in current electricity designed to effect conceptual change. As part of the programme, students were asked to design both circuit as well as wiring diagrams for a doll's house. The wiring diagrams were then compared to the circuit designs and common errors in the circuit diagrams, the wiring diagrams as well as subsequent examination responses to related questions were recorded and categorised according to alternative models of electric current identified in the literature. In this way, both the circuit diagrams as well as the wiring diagrams were used as diagnostic instruments to identify preconceived ideas about simple DC circuits. An analysis of the catalogue of common errors in the circuit and wiring diagrams, suggests that students not only revert to earlier, non-scientific models of thinking about electricity when confronted with the rather more difficult task of spatially organising the components that need to be connected to fit in with the design of the house, but that they also exhibit interesting “transitional” diagrams that incorporate conflicting ideas about circuits. These instances of transitional thinking as manifested in the students' wiring and circuit diagrams might reflect instances of intermediate developmental models used by students, or perhaps the re-emergence of phenomenological primitives. This conceptual ecology that is manifested through a process of designing wiring diagrams could be a useful way to track and facilitate conceptual change in students.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
menyelidiki hubungan antara gaya magnetik dengan kuat arus listrik, panjang kawat penghantar, dan kuat medan magnet. Kemudian dari hubungan tersebut diformulasikan persamaan gaya magnetik. Hasil pengamatan pada kegiatan pertama diperoleh... more
menyelidiki hubungan antara gaya magnetik dengan kuat arus listrik, panjang kawat penghantar, dan kuat medan magnet. Kemudian dari hubungan tersebut diformulasikan persamaan gaya magnetik. Hasil pengamatan pada kegiatan pertama diperoleh data, semakin besar panjang loop arus maka semakin besar pula perubahan massa magnet. Pada kegiatan kedua diperoleh data, semakin besar kuat arus listrik, maka semakin besar perubahan massa magnet. Pada kegiatan ketiga, diperoleh data banyak magnet digunakan, maka semakin besar pula perubahan massa magnet.
Research Interests:
Upload File
Forse siete curiosi di saperne di più sulla natura della Luce o di vedere come se ne misura la velocità: anche e inaspettatamente con un forno a microonde e un pezzo di cioccolato. Oppure potreste voler giocare in modo scientifico a fare... more
Forse siete curiosi di saperne di più sulla natura della Luce o di vedere come se ne misura la velocità: anche e inaspettatamente con un forno a microonde e un pezzo di cioccolato. Oppure potreste voler giocare in modo scientifico a fare i gemmologi, scatenarvi nella caccia al Tesoro della Scienza, visitare un Microcosmo con Vista. Alcuni di voi saranno incuriositi dalla Fisica in Cucina e dai metodi per creare un  gelato perfetto, mentre altri vorranno capire come gestire al meglio le ricche ma limitate risorse che da millenni ci fornisce la Terra. E nessuno resisterà a visitare le stanze della Fisica, dove perfino l’invisibile diviene visibile.
Il 25 settembre vi aspettiamo dalle 15 alle 20 al Parco Area delle Scienze (Campus Universitario)

Forse siete curiosi di saperne di più sulla natura della Luce o di vedere come se ne misura la velocità: anche e inaspettatamente con un forno a microonde e un pezzo di cioccolato. Oppure potreste voler giocare in modo scientifico a fare... more
Forse siete curiosi di saperne di più sulla natura della Luce o di vedere come se ne misura la velocità: anche e inaspettatamente con un forno a microonde e un pezzo di cioccolato. Oppure potreste voler giocare in modo scientifico a fare i gemmologi, scatenarvi nella caccia al Tesoro della Scienza, visitare un Microcosmo con Vista. Alcuni di voi saranno incuriositi dalla Fisica in Cucina e dai metodi per creare un  gelato perfetto, mentre altri vorranno capire come gestire al meglio le ricche ma limitate risorse che da millenni ci fornisce la Terra. E nessuno resisterà a visitare le stanze della Fisica, dove perfino l’invisibile diviene visibile.
Il 25 settembre vi aspettiamo dalle 15 alle 20 al Parco Area delle Scienze (Campus Universitario)

Research Interests:
Research Interests:
The DHAC framework (Development of Habits through Apprenticeship in a Community) builds on the contemporary understanding of teacher preparation and strives to provide a better understanding of the process of learning to teach physics.... more
The DHAC framework (Development of Habits through Apprenticeship in a Community) builds on the contemporary understanding of teacher preparation and strives to provide a better understanding of the process of learning to teach physics. Extant literature on teacher preparation suggests that pre-service teachers learn best when they are immersed in a community that allows them to develop dispositions, knowledge and practical skills and share with the community a strong vision of what good teaching means. However, despite having developed the requisite dispositions, knowledge and skills in pursuing the shared vision of good teaching, the professional demands on a teacher’s time are so great out of and so complex during class time that if every decision requires multiple considerations and deliberations with oneself, the productive decisions might not materialize. We therefore argue that the missing link between intentional decision-making and actual teaching practice are the teacher’s habits (spontaneous responses to situational cues). Teachers unavoidably develop habits with practical experience and under the influence of knowledge and belief structures that in many ways condition the responses of teachers in their practical work. To avoid new teachers developing unproductive habits, directed towards teacher “survival” instead of student learning, or reverting to the “old ways” of teaching learned through the apprenticeship of observation, we argue that a physics teacher preparation program should strive to develop in pre-service teachers strong habits of mind and practice that will serve as an underlying support structure for beginning teachers. In the paper we provide examples of the habits, which physics teachers need to develop before starting teaching, and connect them to the knowledge, skills and dispositions required for their development. Using the DHAC framework, we explain the features of successful physics teacher preparation programs and predict the outcomes of different approaches to teacher education.
Research Interests:
Combining an interactive whiteboard with the right software, and with an appropriate instructional approach, is crucial for its productive use in physics classrooms. We describe how the interactive whiteboard can be used in combination... more
Combining an interactive whiteboard with the right software, and with an appropriate instructional approach, is crucial for its productive use in physics classrooms. We describe how the interactive whiteboard can be used in combination with a physics-based sandbox software program (Algodoo) to address the topic of Kepler's laws. The proposed activity engages students in collaborative inquiry and draws on students' experience in using touch-screen technology. Students engage in the manipulation of virtual objects on the interactive whiteboard and investigate Kepler's laws by actively participating in the creation of planets, sending them into orbit, and representing their motion using a wide variety of virtual tools.
Research Interests:
Un repaso por la óptica y las matemáticas con actividades lúdicas
Research Interests:
Academia © 2015