Preparing specs for developers of 'pull to refresh' and flick gestures. I'm trying to figure out how to spec these out. Compared to defining normal animations like movement with time and distance this is more complex.
I think you are talking about something which is available in jQuery, which they call "Easings" https://api.jqueryui.com/easings/
In this website the movement is communicated using a diagram which animates the movement when clicked. There are variations which include things like bounce and elasticity.
Basically the variable you are missing is the rate of acceleration, which can vary throughout the animation, e.g. start slow, speed up, then quickly slowing down, before bouncing, etc.