# Elastic collisions

(Blender version 2.65.0)

I’ve set up a very simple system. I have a cube (rigid body) above a plane (static). I let the cube fall and it bounces repeatedly. My problem is that I can’t make sense of how high it bounces.

With the elasticity of both items set to 1.000 the cube’s bounces get higher and higher.
With the elasticity of both items set to 0.900 the cube’s bounces decay.

OK, I thought, there’s a slight error in their bounce algorithm and elastic collisions occur wiuth an elasticity value somewhere between 0.9 and 1.0. Time for a binary search, I thought. Poor, maive me…

With the elasticity of both items set to 0.950 the cube’s bounces start to get stronger and then decay again. After a bit the bounces increase again, then decay for a bit, etc.

My ultimate goal is to illustrate a physical system with a largish number of rigid spheres bouncing about inside a static/rigid box. I need individual collisions to obey the laws of physics.

Is there some magic settings for “be physical”? Or is there some other switch I’m missing?