The first moment I heard about the new topic for the current #31 BlenderArt Magazine, I was like 'Cool, I have to participate!' Unfortunately I didn't know how to contribute some-thing. But since currently I'm attending a vocational school in Nuremberg, Germany, finding a suitable topic was not such a big deal. Furthermore, I think that I will deeply benefit from this. On the one hand I can improve my physics skills and on the other hand my English skills. Ah, and of course my Blender skills as well!

Approaching the animation

So I sat down and thought about my animation concept. Since we were dealing with circular motion in physics and I knew that my classmates and I had several problems with applying the corresponding laws, I decided to stik to that topic. With the formulas lying in front of me, I started to write the script. I had to think about a didactical (teaching) structure and at the same time how to visualize it in Blender.
In the end, the speaker text took up a whole page and after the first audio recording I was able to start the realisation in Blender. The cool thing with these projects is that Blender has an internal video sequencer, where you can just put all of your audio files and play them bak in real time. Because of that, there weren't any synchronisation problems and the animation process was very comfortable.

Physics of Circular Motion-1.jpg

I wanted to keep everything as dynamic as possible, so I looked for constraints to help with the animation. Finally I used a 'Follow Path' constraint and took the opportunity to keyframe the offset parameter. To scale the vectors against the radius of the circle, the 'Copy Scale' constraint did a great job. But I had to set keyframes for the influence to stay put at 0 until the respective vectors are mentioned, because otherwise they would scale up too early, e.g. when scaling up the radius of the circle when the radial acceleration has not been mentioned yet.
The rest was made by creating keyframes to animate the vectors and using shape keys for the Pythagorean theorem. It turned out that I had forgotten to change the frame rate to the European standard of 25 frames per second. Because of that I had to readjust all of the keyframes. That's why it's essential you set up your render settings before you begin animating. This brings us to the problems I had to face in the animation process.

Physics of Circular Motion-2.jpg


Fortunately, since Blender can save the sound into the final video due to its sequencer, there was only one big problem: The text animation.
I decided to do it in After Effects, which turned out to be a very time-consuming process.
After Effects doesn't support the audio playbak in real time, at least not until CS3. So I had to switch on the display of seconds in the timeline in Blender and tweaque all of the fade in and fade out animations in After Effects synchronously while scrubbing through the animation in Blender. Hopefully in future, Blender will get a sophisticated tool to add some text in the compositor to avoid third party software, which brings more trouble than it actually helps, at least as far as synchronisation is concerned.

Physics of Circular Motion-3.jpg


To conclude, the development of this video was a rather simple task. Blender was a great aid with its builtin animation features allowing for a dynamic, customisable animation process. I really appreciate Blender’s big arsenal of tools and the organised graphical user interface. It's an indispensable Open Source graphics suite that everybody should use and support.
I'm very enthusiastic about it and founded the first Blender user group in Nuremberg with some other guys and I'm trying to establish a quality German video tutorial website to increase the number of Blender us-ers in Germany. Thanks to the Blender Foundation and all of the developers!!! You can watch the animation here: