Macroscopic Estimate of the Average Speed for New Particles Created in   Collision
  A {\it heuristic} approach is proposed to estimate the average speed of particles during binary encounters by using the macroscopic variables with their extended gradient-type which are the fundamental independent variables in {\it extended thermodynamics} theory. We also address the missing contribution (say, due to creation of new particles : {\it Acoustons}) in conventional Bremsstrahlung. 
A. Kwang-Hua Chu