The expressions simply check the velocity of your animations. If you move an objects motion ends abruptly (ie: you didn't easeIn @ 100%) the physics will kick in automatically.

This script creates one new layer for each selected layer in the active comp. Each layer contains an arrow that gives velocity feedback.

Essentially, Inertial Bounce creates a bouncing motion of any parameter from one keyframe to the next, based on its velocity.

If you want to use the speed/velocity of a layer's movement to drive an effect ...

These expressions save so much time, you might get home earlier tonight just by reading this.

Most people don't know about the loopOut and loopIn expression methods...

Using Trapcode Particular and a Beveled stroke created with Write-On, Harry J. Frank created this pretty, pretty flower.

This is a variation on the pendulum expression.

Keyframes were applied to Jack's position at frames 0 and 1 to move him out of the box

This is an expression you can use to generate a decaying pendulum motion.
by Dan Ebbert