Mobile Game Physics
Using mobile games to help understand physics

This is something that I have been wanting to do a long time now but I finally have had the chance to do so. The idea is to take a mobile game with a moving object or character and try to determine some movement such as a horizontal movement, fall or parabolic motion.

I am not sure where I got this idea but I know that I did not come up with it. So credit to the person I had a conversation with or the website the I viewed.  I certainly wanted to try this myself.  In the process of putting this together, I want to make sure that everything I use was free.

There were three general steps involved in carry this out:

  1. Record the motion of a game using an app
  2. Import video into a video analysis software
  3. Export the data to Google Sheets

As a classroom teacher I am of hesitant to do 3 steps like this. It would certainly be difficult to do it the first time with the students  or certainly it would require a fair amount of training to get the students the skills necessary to do it. Perhaps the novelty of the experience might be useful enough to help motivate the students to get through the complicated parts of this task.

The whole process for me took roughly two and a half hours from the moment of recording the game all the way to analyzing the physics. I must say that it was more complicated than I thought it would be and I feel that there are probably better Solutions out there.

Materials used:

  • Tablet or cell phone
  • Select a game software
  • Screen recording software
    • Android Suggestion – DU Recording
    • Apple Suggestion – Apple makes it easier to record the screen after IOS 10 update. There is a feature embedded in the OS called “Screen Recorder”.
  • Video analysis software
    • Android – VidAnalysis
      • This app is functional and free but I am not satisfied with it.  The struggle was tracking the movement. As one clicks on the moving object, it is difficult to be accurate. There is no way to zoom in on the object to be more detailed in selection.
    • IOS – I could not find a decent free graph analysis application. Vernier makes a good quality app but is cost $5. The goal was to make this experience with no cost.

Toy Car RC Animated GIF

For the purposes of this post, I will be using a game called Toy Car RC. One could conceivably use other apps such as Angry Birds or even Flappy Birds (Do you remember this game?) which show simple motion within the game mechanics. Toy Car RC application like many other VR applications require the user to establish makers or targets on the the floor. As you can see with the animation above, I used two (yellow envelop and blue copy paper package. I addition the two targets, I needed to establish a distance reference point. I thought about using the floor tiles but I decided to be more official with a meter stick. As you can see the little car’s motion roughly runs in parallel with the ruler. It took me a few times just to get this car as straight as it is now. I finally figured out that I could just tap the screen and it would go straight across. I wish I would have known about this earlier.

The next step was to use a screen recording application to actual record the car being controlled. It records the screen as a video for which I can import it into my video analysis software. As mentioned earlier, the software was difficult to use. After all of the data points where establish, I exported as a .csv file and imported into Google Sheets. Here is the link to the raw data and graph. The data output was strangely place in scientific notation. As of the time of this writing, I could not find a way around this.

As you can see on the graph below, the data seems fairly consistent. Currently I have it set at a constant velocity by the trendline but it looks a bit curved which would imply an acceleration.  The actual average velocity of the car is around 0.5 m/s.

Just for fun I did a velocity over time graph. The acceleration is more obvious on this graph.

The overall the process was more tedious then what I would feel comfortable having the students to do. There were too many steps that the students would have to take in order to see the whole experience through. The amount of training required to get the students would also be a time consuming as well. I would consider doing something like this in my class if I could eliminate at least one of the steps. Using the Vernier app would eliminate one of the steps. I am currently using Android which Vernier does not make their software available for it and it is not free.