Photogate de baixo custo com a porta de jogos do PC (Low-cost gameport photogate)

We present in this work a low-cost device for measurements of time intervals, velocities and acelerations, useful in the free-fall problem and others experiments in mechanics. We have constructed a homemade photogate using the PC gameport to make data acquisition and to obtain the acceleration of gravity. We have obtained good agreement of the experimental data and theoretical model of a free falling body. Our work provide a way to measure short time intervals with good accuracy, and open new possibilities of applications in physics teaching.