I'm in the process of conducting research concerning free fall with air resistence. I'm dropping a beach ball filled with air from certain heigts, while measuring its speed and acceleration during the fall.
Theoretically, the initial (first few milliseconds) acceleration of the beach ball should be "g" (9,82 m/s^2). However, I am measuring an initial acceleration to be 6,5 m/s^2.
How come the empirical initial acceleration, does not equal the theoretical initial acceleration? My first guess was that the buoyancy has something to do with it, but there has to be more, since the buoyancy alone does not make up for it.
What can it be, that stops the beach ball from having "g" as its initial acceleration?
EDIT: I now realize, that I haven't done a very good job explaining my experiment, nor have I given any information concerning it. So here are the things that I haven't mentioned yet, maybe that can solve the problem.
First of all, I am actually NOT using a volleyball, but I am using a beach ball.
How I collect data: I install a motion sensor on the ground and connect it to a computer. I then lift my beach ball to a certain height, and bring it above the motion sensor. I then drop the ball, and let it land on the sensor. The sensor then spits out a lot of data, including velocity, position and acceleration during the entire fall of the ball.
Information concerning setup.
- Mass of ball with no air inside: 0,004856 kg
- Mass of ball full of air: 0,004924 kg
- Height ball was dropped from: 1,5 m
- Initial acceleration: 6,5 m/s^2
- Volume of beach ball full of air: 0,009655 m^3