We present a set of experiments spanning a broad range of areas of physics that can be carried out using either a digital camera or a web cam. Among them we study the trajectories of water jets, the profile of hanging chains and caustic figures produced by the reflection of light on mirrors of different shapes. This pool of projects shares a common methodological approach and allows for a simple quantitative comparison between theory and experimental results. Since digital cameras are comparatively lowcost laboratory equipment and have become progressively more available, many schools and colleges with limited experimental facilities may benefit from the very costeffective and challenging projects presented here.

We present an experimental method to obtain the effective mass of an unloaded oscillating spring. We measure the period T(n) of the partial springs that result when hanging n of the total N coils of a given spring. Data are correlated with the expectation of a simple model for T(n) that takes into account the effective mass of the hanging spring. We analyze results for metal and plastic springs of different masses and strengths, and conclude that the method provides the effective mass with a good degree of reliability.

The bead on a rotating hoop is a typical problem in mechanics, frequently posed to junior science and engineering students in basic physics courses. Although this system has a rich dynamics, it is usually not analysed beyond the point particle approximation in undergraduate textbooks, nor empirically investigated. Advanced textbooks show the existence of bifurcations owing to the system's nonlinear nature, and some papers demonstrate, from a theoretical standpoint, its points of contact with phase transition phenomena. However, scarce experimental research has been conducted to better understand its behaviour. We show in this paper that a minor modification to the problem leads to appealing consequences that can be studied both theoretically and empirically with the basic conceptual tools and experimental skills available to junior students. In particular, we go beyond the point particle approximation by treating the bead as a rigid spherical body, and explore the effect of a slightly non-vertical hoop's rotation axis that gives rise to a resonant behaviour not considered in previous works. This study can be accomplished by means of digital video and open source software. The experience can motivate an engaging laboratory project by integrating standard curriculum topics, data analysis and experimental exploration.

Tomosíntesis digital de mama (DBT) es una tecnología relativamente novedosa y para realizar controles de calidad de las imágenes obtenidas por ese equipo, se requieren fantomas específicos de 3 dimensiones que simulen lo mejor posible las mamas de las mujeres. El objetivo de este trabajo es diseñar fantomas virtuales (in-silico) en base a imágenes obtenidas con un sistema DBT , para utilizarlos en la fabricación de fantomas antropomórficos de mama con materiales elastoméricos tales como polivinil alcohol y silicona. También se adquirirán imágenes DBT para entrenar un modelo de análisis basado en el aprendizaje de máquina. La calidad de los fantomas construidos se validarán a partir de imágenes mamográficas. Finalmente, se realizarán pruebas de fuerza de compresión y calidad de imágenes empleando los nuevos fantomas.