A device for studying the free fall of objects under controlled pressure conditions. The system uses laser diodes and phototransistors to measure time in microseconds. Controlled by a microcontroller, the system allows the user to release an object and plot space-time and velocity-time curves, or obtain the acceleration due to gravity immediately. The system allows measurements to be taken into account five variables: time, mass and diameter of the object, distance traveled, and the pressure at which the experiment is performed.