Gravity Test with Golf-ball
Objective
The goal of this project is to compute the value of the gravitational acceleration with an indirect approach. Since acceleration is the second derivative with respect to position, if initial position and initial velocity are known, it’s possible to find the acceleration integrating twice the acceleration. The only unknown remained is the time. The resulting formula (considering initial velocity and final position equal to 0) is a = 2ΔS/t2 . In this project the main goal is to make a golf-ball to fall, compute the time it takes, and then get the acceleration.
Our Strategy
Each group was free to invent a method to compute the time it takes for the golf-ball to fall from the table, the only constraint was the time, since we were given only 1 hour to make it. Me and my teammate came up with a simple solution. We created a small circuit using Arduino, 4 wires and some aluminum foils. 2 of them were kept parallel and very close to each other near the table where the ball was starting. We wrapped the ball of aluminum so before the experiment was starting we were keeping the ball attached to the 2 wires and current was “flowing”. On the floor we created 2 levels with aluminum foils, each of them attached to a wire. When the ball was falling, it was making the upper foil touch the bottom one, shorting the circuit. In this way we were getting with a simple Arduino code when the ball was leaving the table level and arriving on the floor. The difference between the 2 absolute times (millis() function in Arduino) was the time we were looking for.
Our setup.
Results
We did several trials and we obtained an average value of 9.72 m/s2, very close to the recognized standard of 9.81 m/s2.
Video Example of 1 trial.