@vipera2006,
This is ridiculously easy to test out. Why don't you do it?
Buy a toy rubber balloon (you can get a bag of them for under $2 in a local store). Blow it up and tie it. It will then be filled with air... mostly Nitrogen is very compressible and will remain a gas (assuming you play with your balloon in room temperature).
Take a weight... I would use a bolt from my toolbox, or even a quarter (I might want to find something a little heavier). Tape it to the balloon.
Add energy to the system by pushing down on the weight. Then release it. The energy you added will turn into kinetic energy, which will then be turned into positional and mechanical potential energy.
If your theory is correct, the weight will continue moving forever (probably oscillating) once you release it.
So... just do the experiment. Please report back here... before publishing your results and collecting your inevitable Noble prize.
