Educational apparatus for the freefall study with motion analysis

This paper presents an experimental project for the electronic measurement of free falling objects for educational purposes. The apparatus consists of a PVC pipe, within which the objects are released. Switching sensors were placed inside the tube at regular distances. Objects passing through them trigger a signal, which is collected, processed by the Arduino platform and sent via serial port to a XBEE module. This send data remotely to another XBEE module attached to a USB port in a computer, where a program calculates the acceleration of movement and serves as user interface. An original solution was devised to avoid interference among sensors. As case study, measures of the gravitational acceleration were made with objects of different geometries. Models with and without air resistance were employed and drag coefficient was obtained