THERMAL PHENOMENA IN CENTRIFUGATION
It is shown that the temperature gradients caused by the heating of an angularly accelerated gas due to compression and the converse cooling of the decelerated gas have appreciable effects on isotope separation factors as determined by centrifugation. These effects were found to be greater than would be indicated by the isothermal theory. The influence of these non-uniform temperatures on the performance of flow-through centrifuges is discussed. (C.J.G.)
Summary. This paper presents some results of a case study about the characteristics of the interactions between pupils in groupworks, in the context of an innovative teaching experience of Physics at university level. Videorecordings were carried ou t during classes of the unit on Thermodynamics and some pupils from a focal group were interviewed. Analysis focused on group processes from the linguistic, social and cognitive perspectives. Results suggest that sharing cognitive processes by a group o f student, through reasoning and argumentation, may be an answer to the challenges of teaching practice at university level.