Apple Motion 3 - Manual (Page 488)

488 Chapter 5 Using Behaviors
4 Apply the Gravity behavior to the “circles 1” group.
The motion path created by the Gravity behavior appears in the Canvas, and the group
of circles falls when you play the project. Because the behavior is applied to the group,
all layers in the group fall at the same rate.
5 To increase the rate of the falling layer, drag the Acceleration slider in the Gravity HUD
or Inspector toward the right (this example uses an Acceleration value of 100).
Note: You can enter a negative number in the Acceleration value field in the Inspector
to make the layer float upward rather than fall.
To use the Edge Collision behavior:
1 Apply the Edge Collision behavior to the “circles1” group.
2 In the Edge Collision HUD (or Inspector), turn off Affect Subobjects.
Gravity behavior applied to group (not to
individual layers of the group)