Abstract In this article, we point out an interesting solution for the dynamics of a racecar in a banked circular track with banking angle well over 90°. We call this track configuration an Inverted Track, at which a racecar can drive partially upside-down. We show an experimental setup, where we made a toy car to circulate upside-down held only by its friction to the track. We discuss the viability to perform the aforementioned stunt with a real racecar in terms of the velocities required, dimensions of the track and safety; provided a passionate motorsport related company to commission it. For most racecars, the aerodynamic down-force is significant and it is included in our analysis.

A solução para a distribuição do potencial em uma configuração de eletrodos esfera-plano é brevemente revisada e é obtida em detalhes usando-se o método das imagens. Uma vez que o potencial é obtido, o campo elétrico, a capacitância, a energia do sistema e a força entre os eletrodos podem ser deduzidos prontamente. E feita uma análise da convergência do potencial, como função do número de imagens consideradas no cálculo. A solução é ilustrada com figuras, representações esquemáticas e exemplos numéricos.

The solution for the potential distribution between a spherical and planar electrode is briefly reviewed and derived in a simple way using the method of images. An analysis of the convergence of the potential, as a function of the number of image charges accounted, is also performed. Once the potential is obtained, the evaluation of the electric field, capacitance, energy of the system and the force between the electrodes is straightforward. The solution is illustrated with pictures, schematic representations and numerical examples.