Superposition free fall and throw

With the apparatus it is possible to make very well audible that a horizontally thrown ball and a free falling ball hit the ground at the same time.
The device is also very suitable for measuring the fall time with PhyPhox and the acoustic stopwatch.
https://phyphox.org/de/experiment/akustische-stoppuhr/

Position the aparatus at the corner of a table, tension the arm, position the balls, press the release-button.

One ball falls straight down, the other flies straight ahead.

You can print both parts in PLA, but PETG is better for the arm.

Print the arm with 5 perimeters, so that the spring is stable.

See it in action: 

In the following graphic you can sea measurements of the falling ball made with the acoustic stopwatch: