Note from 29 Oct 2018: this post was originally drafted in 2014 and fell by the wayside; recent developments in Tracker derivatives on Chrome have brought it back to the forefront of my mind. Tracker is the most powerful, GNU GPL licensed (free and open) video analysis software I have used. It is more powerful than some commercial software with video analysis. The killer feature for me is auto-tracking, which is implemented with some intelligence built in.
Updates to come soon on a browser-based derivative of Tracker that is being developed by Luca Demian as discussed here.
Good video analysis is one of the best things to happen to physics teaching, learning, and understanding, it makes it so much easier to really dig into how objects move and interact.
Things don’t always go perfectly smooth — the auto-fit for this data was completely wrong, so I estimated values for the coefficients and constant in the sinusoidal model and then tweaked them to achieve a good fit. In doing so, it helps reinforce what the different coefficients in the model stand for and do.
In this example, the physical setup is an eleven coil section of a Slinky, salvaged from one that had been hopelessly tangled in the way we all know happens all the time.
The thought from that old draft was never finished, and I may have lost my notes from that experiment — but I think the tool is important and worth sharing. If the notes show up…I’ll continue the thought. -JD 29 Oct 2018