I am thinking of a system of isolated, moving, and colliding particles in a frictionless box. The collisions were inelastic. My question is:
Supposing that the initial total momentum of the system is not zero. Since the collisions are inelastic, kinetic energy will not be conserved (converted to heat, sound, etc.). But since the isolated system experiences no net external force, the momentum could not change (Newton’s Second Law). Hence, total momentum of the system will remain constant. If I let the particles in the system collide for awhile, eventually, they will build up heat, but then again the momentum could not change. The particles would not stop until the box overheats.
What’s the problem with the scenario and my line of thinking?