2014-07-292008-12-082008-08-29MARTINS, Tiberio Bittencourt de Oliveira. Motions under focal attraction in planar vector fields. 2008. 70 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de Goiás, Goiania, 2008.http://repositorio.bc.ufg.br/tede/handle/tde/1971In this work, we develop the article On the motion under focal attraction in a rotating medium , of J. Sotomayor, which deals with a bidimensional differential system that model the following Biological problem: in a shallow recipient with circular section, with liquid in, spinning with angular speed ω, there are platyhelminthes, flatworms organisms, they are attracted by a fix lighting point near of the border of the recipient and they swim with a speed v in the direction of the this point. The problem is to show that there exists an equilibrium point where platyhelminthes go to cluster by the time passing. It s analyzed the dynamic of the model: existence of critical points and stability of the system and bifurcations. We analyzed three modifications of this system too. In the last part, it s discussed a criterium for non existence of periodic orbits of a planar vector fields in a simply connected region.application/pdfAcesso AbertoCampos vetoriais planares BiologiaEquações diferenciais bidimencionaisDinâmica de modelagem PlatelmintosFold, Pitchfork and Bogdanov-Takens bifurcationsCampos vetoriais planares Biologia; Equações diferenciais bidimencionais; Dinâmica de modelagem PlatelmintosCNPQ::CIENCIAS EXATAS E DA TERRA::MATEMATICADissertação