## Thursday, August 20, 2015

### How to do Video Screencast and Analysis of a Video Game to Determine the Physics

One of the primary tools STEM classes have to analyze various phenomena is video. With the cameras on cell phones, for instance, many new devices have high-speed options for video, such as up to 120 or 240 frames per second (fps). The same for most cameras and camcorders one can purchase as the prices come down.

This video gives another fun option to do some physics while playing video games. When playing an online game, you can use Screencast-o-matic to create a screencast video of you playing the game for a few seconds. Screencast-o-matic is nice because you can use it for free and do not have to download anything - just click 'Start Recording' and it begins!

With that video, you can import it into a program called Tracker, which can be downloaded onto your computer for free. Some schools may have Logger Pro, which is the software for Vernier sensors, and that has video analysis capabilities. Whatever the tool, check this out to see how Tracker can be used within a few minutes to get data for the game Asteroids, to find the speed of the spaceship. You can set size scales to make the scene as realistic as you wish. In the case of Asteroids, you can look up average sizes and densities of asteroids, find the size within the video game based on your size calibration and scale, and then determine the masses of asteroids. You could look up and use a reasonable size and mass for a spacecraft (many often use the space shuttle, looking it up in Wikipedia). Then, with those data, you can calculate speeds from motion graphs in Tracker, which leads to accelerations, forces, momenta, kinetic energies. You could calculate the gravitational forces between asteroids and your ship - are those significant? If so, does the video game account for those forces, or is gravity ignored? You could have some fun and calculate how much you would weigh on one of the asteroids, and what the escape velocity is - would you be able to jump off the asteroid and into space?

You could do a similar process and analysis with a billiards video game - and then determine from measurements in Tracker whether or not momentum is conserved, or if energy is conserved, and so on. You could also take video of a real game of billiards, or anything in life that has motion, and begin analyzing the video to see the physics! It is a really useful and powerful tool we can use for anything in life and any experiments we do in class. I hope this helps!