A rubber ball, with a 4.9‐cm diameter and 64‐g mass, is dropped from a certain heighthto bounce onto the floor, and the time between the first bounce and thenth bounce is measured. In the first version this time is taken by a digital stopwatch with one centisecond resolution, and in the second version, by an integrated‐circuit timer with 1‐ms resolution, triggered by a microphone. Considering the formulah=(1/2)gt2and the coefficient of restitution of energy in the collision of the ball against the floor, the acceleration of gravitygmay be determined to 2%–3% in the first version and to better than 1% in the second one. The experiment opens many problems, i.e., about the time of contact, the internal vibrational energy of the ball, and the dependence of the elastic properties of the rubber on the temperature.