I like the idea behind the game, but I think it could be a little better designed. I have a few random suggestions you could use for your sequel.
For instance, I found the three-track interface to be much too distracting and difficult to play with. One way you could solve this is by putting all of the movers in one screen. By putting them together, it actually becomes easier to see how their movements all relate to one another. So the playing field would be set up like this:
[Top of screen: objects fall from here
[
[
[
[
[
[
[
[Position mover slides on this line
[Velocity mover slides on this line
[Acceleration mover slides on this line
[
[Bottom of screen
Also, the sound each falling object creates depends on which mover hits it: Lead for Positional, Drum for Velocity, and Bass for Acceleration.
There is also only one type of powerup, but powerups have different effects depending on which mover hits it. If a powerup hits the acceleration slider, the acceleration rate is increased, meaning the position mover will speed up and slow down more rapidly. If a powerup hits the velocity mover, the positional mover will have a higher maximum speed. Finally, if a powerup hits the positional mover, the playing field will expand horizontally.