In this paper, the velocity and acceleration of four water rockets is determined, using the least squares method and the Euler’s method. The position and time data are obtained from the analysis of slow-motion videos of the launch of the rockets, processed with the video analyzer software “Tracker”. This experiment is proposed as a pedagogical tool for the exploration by students of high school and first semester of sciencie and engineering of basic concepts of kinematics and dynamics in systems with variable mass and acceleration.