Simple experiment and simulation of a rotating liquid's free surface

This work explains an easy and cost-effective method to investigate the behavior of the free surface of a liquid in a rotating container. By means of two standing cameras, we recorded the movement of the container from top and the changing profile of the liquid surface from lateral view. In the resulting videos, we noticed the usual parabolic shape of the free surface, characteristic to rotating liquids. The videos were then analyzed by employing the Tracker software and we found the rotation period of the container and the displacement of the parabola apex with respect to the initial standstill position. From the acquired data we were able to calculate the gravitational acceleration with excellent precision. For the second part of the work, we created a Python script for simulating the same experiment. The user can interactively change the involved main physical parameters, observing the implicit modification of the parabola’s shape. Our work proposes a didactic alternative approach for studying and simulation of a rotating liquid free surface, while the attained results are comparable with the ones obtained by traditional methods.