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Sunday, May 21, 2017

Video analysis and the mass of the moon

We will investigate physics through the use of video analysis. The reasons for doing this includes a primary one of using Logger Pro software, which the school has from the Vernier electronic sensors, to do a video analysis. I want you to realize you can take any YouTube video, or any video (or digital photo) you take with your phone, and analyze any type of motion in any event you capture! This is a powerful tool that we all have access to in this day and age, and allows us to do so many more analyses. And with high-speed video options that more phones are providing, such as 120 frames per second (fps), 240 fps, and even 480 fps, or digital cameras that now provide 1000 fps or more, we can use video analysis software to look at finer details of motion than we ever could before in a high school lab. Keep in mind that a normal video is around 30 fps.

Watch this video for getting an introduction to using Logger Pro for video analysis.

One thing I recommend is to download a free piece of software called Tracker on a home computer (cannot do this with the Chromebooks, unfortunately), so you have the chance to check out details if you ever get the urge. This is an introductory video for using Tracker.

All you need is a few seconds of video to get into an analysis. For today we have as a goal to figure out the mass of the moon, perhaps using the original video footage of the first men on the moon in 1969! All you need is a bit of projectile motion to figure out the acceleration due to gravity, and the fact that the radius of the moon is 1079 miles. Work with a partner, and keep in mind you need to Google some conversions and get the mass of the moon in kilograms based on data from the video.You can use any moon landing video you want, including the moon buggy, dropping a hammer and falcon feather, or any other that involves some gravitational action you can use to figure this out. Also come up with a percent error compared to an accepted value of the moon mass.

Note that to import a video clip into Logger Pro or Tracker, you need to have the video file. To get this from your phone, of course you would need to just upload the video to your computer and then import into the software. For a YouTube video, you can make a screencast video file of the YouTube video, and save it to your computer. A quick, easy way to do this is to use Screencast-o-matic. Just select the brief scene you need to do the analysis, and capture it with the screencast! Here's a how to video for making a Screencast-o-matic video, which I suggest saving to your desktop or to your student My Documents folder. You will be able to Insert this video file into Logger Pro.


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