One more time.
http://knol.google.com/k/alex-belov/the-wheels/1xmqm1l0s4ys/18#Base on trivial case of problem, the figure 4 shows a model for experiment where wheels and solid block covers by another platforms on wheels.
The wheel1_1 and wheel1_2 connect with cover by axis.
For easies calculation, all doted elements, platforms and spring are weightless.
Let's assume the law of momentum conservation always works in simplest form. In this case, the forces on both sides of spring are equal by value and induce translational motions for solid block and rolling objects on both platforms. However,
which force induce rotational motion for rolling objects on one platform? The solid block doesn't conduct rotational motion on other platform. On one platform, the rolling objects rotate on opposite direction for each other and have same angular momentum by value and opposite direction. However,
need a force to induce this rotation. The asymmetrical force cannot exist during interaction. Therefore, the assumption where law of momentum conservation exist in simple form during complex interaction is wrong.
