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Video Analysis: The Good, the Bad and the Ugly
If you record videos for your physics analysis, there are some things you just shouldn’t do. Let’s go over those “wrongs” so you can make a video that’s right.
The Physics of Video Analysis
Here is my super quick intro to video analysis. The basic idea is that you can get x-y position and time data by looking at the location of an object in each frame of a video.
Although it’s possible to just use a ruler and measure the location of an object on the screen of your computer (that’s the way they did it in The MythBusters), there are other options. First, there is Tracker Video Analysis. This is a free video analysis program that either runs using java on your computer — OR, you can use their online interface (so you don’t have to install java).
With that, there are two important things you need to get the data. First, you need to know the time between each frame of video. This is easy since most of the time (but not always), the playback speed and the record speed are the same. So, the frame rate (fps) is in the video. Second, you need a real distance scale. Notice that in my pictures above, there is a meter stick on the wall. That way I can figure out the actual distance for each pixel motion in the video.
