This Balloon was an experiment I did playing a bit with Verlet physics (if I can catalogue the Verlet concept as part of physics). Using Verlet can be quite powerful but at the same time is a bit limited due to the simplicity of how physics are applied, we don't have much control of it and for adjusting stiffness between dots we need to do quite much, there are some people out there working a lot with it and making amazing things like this physics engine for action script 3.