Apple Motion 3 - Manual (Page 748)

748 Chapter 8 Working with Particles
14 Use the following illustration as a guide to adjust the Emission Range and Angle so the
particles appear to follow behind the emitter.
The result should look something like this:
You may want to adjust the Emitter parameters for Birth Rate, Life, and Speed to
customize the effect to your liking.
To turn the system into 3D particles:
1 In the Emitter Inspector, turn on 3D.
3D checkbox