In hydrostatics, pressure measurement with U-gauges and their relationship to density is a
well-known experiment. Very little is studied or experimented with the dynamics of the movement of a
liquid in a U-tube probably due to its theoretical complexity but, after all, it is a simple damped
oscillating system. In this paper we present a relatively simple experiment that allows studying in
some detail the dynamics of the movement of a liquid in a U-tube when an initial pressure gradient
is applied. In order to record the information of the column displacement as a function of time we
have developed a position sensor system based on a solar cell that allows the recording of the
experiment using a simple data acquisition system.