Hasta La Motion!

I have a small problem tackling inertia and bounce with an expression.
There are some scripts written for after effects but they base on velocity which I do not have in nuke.
I managed to write sth but it is far, far from usable as it takes way too many arguments.

Problem I have.
We have two points on x axis (just for the sake of simplicity).
One is moving with a keyframed animation. The second should follow BUT:
– the second point should have inertia that makes him bounce around every time it has to stop
– the second point should react like it is connected with a rubber string with the first point. So it moves some time after the first point and moves faster when points are further appart

I have found a way to express inertia bounce with sth like this (all values come from a NoOp node that has custom knobs):

but as I wrote earlier I had to add a lot of other things into the statement to make the bounce visible.

I hope I wrote it clearly enough and someone can help me with it.