I'm trying to find the right word / concept to describe the following effect:
Consider a pendulum, except with each swing it gains momentum. The exchange of potential and kinetic energy is not equal, instead increasing with each shift.
Another way to describe the concept: you're trimming a bush and you want it to be symmetrical. You take a little off the left, you take a little off the right, then you step back and --crap, it's uneven. So you take a little more off the right and --crap, uneven on the left now. You keep going until you don't have a bush anymore, just a weird amalgamation of branches.
Surely there is some physical or social scientific term that describes this concept. I've exhausted my Googling capabilities, can anyone offer guidance?