About controlling Simulation behaviors
The ideal use for behaviors (with the exception of Motion Tracking behaviors) is creating fluid motion graphics that do not require specific timing. This is especially true with the Simulation behaviors, which let you create sophisticated interactions among multiple objects in your project with minimal editing.
Unlike Basic Motion behaviors, you cannot stop or change the motion of a Simulation behavior in the Timeline. However, you can affect the rate of a Simulation behavior by modifying its duration in the Timeline. You can also change the starting frame of the behavior.
Because the Simulation behaviors mimic natural effects, such as Gravity, the laws of inertia apply: an external force sets the object in motion, and that object stays in motion even after the active force is no longer present. Changing the duration of a Timeline bar for a Simulation behavior does stop the “active” force on the object but does not stop the motion of the object. You can, of course, control Simulation behaviors by modifying their parameters.
In the following image, the Orbit Around behavior is applied to the small blue circle. The large orange circle is assigned as the object that the blue circle moves around. The red animation path represents the motion of the small blue circle over its duration. The Orbit Around behavior is the same duration (240 frames) as the large circle to which it is applied.
In the next image, the Orbit Around behavior is trimmed in the Timeline to a shorter duration (140 frames) than the object to which it is applied. Notice the change in the shape of the animation path: At frame 140, where the Orbit Around behavior ends, the object (the small blue circle) stops moving around its target and continues moving off the Canvas. The Orbit Around behavior—the active force—is no longer present, but the motion of the blue circle does not stop.