2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/18072We present an analytical approximation for nonlinear dynamics of trapped Bose-co ndensed gases. The new approximation is a substantial improvement over the Thomas-Fermi approximation and is shown to be applicable for systems with a rather small number of atoms $N$. The calculated aspect ratios after ballistic expansion are found to be in good agreement with those observed in recent experiments.10 pages, 1 figure, 3 tablesStatistical Mechanicstext