Inelastic Collisions are the Norm
Traditional kinetic theory wrongly considers that all collisions between gaseous molecules are elastic, i.e. energy is conserved. For any elastic collision, the relative velocity of the two colliding masses before (collision) equals the minus of the relative velocity after the collision. Another way of considering an elastic collision is that both the momentum and kinetic energy are cosnserved. This is different than an inelastic collision where only the momentum is conserved.
From classical
mechanics we know that when two dissimilar objects, i.e. masses M1 and M2, collide then their total momentum is conserved, therefore
in terms of their velocities (v1 and v2):
v2=(M1/M2)v1 Or v1=(M2/M1)v2 1.10.36
A better understanding of elastic vs inelastic collisions is given in pdf to the right which is an appendix given in my book "New thermodynamics: Say no to entropy".
This author has shown that kinetic theory is better explained by realizing
that collisions are inelastic in which case momentum is mechanically conserved but kinetic energy is not i.e. the total kinetic
energy after the collision does not equal the total kinetic energy after the collision. See papers on kinetic theory. see blog
on kinetic theory.
Furthermore, collisions between gas molecules with different masses is not readily envisioned. This is all discussed
in more detail in my book. So although a plausible solution for elastic collisions exists, the assertion of their reality remains
questionable. The more logical solution becomes that intermolecular collisions are not elastic, and that kinetic theory retains its
absolute validity simply because the gas is sufficiently dilute that the predominate energy exchange is the surrounding wall molecules
imposing their kinematics onto the gas molecules.
Now imagine; when gaseous molecules do collide that heat is given off, hence
such collisions are not elastic, but energy remains conserved. If inelastic collisions occur within a closed system, then the other
gas molecules and/or the surrounding wall molecules should absorb any collision derived heat that is given off. Accordingly, such
collisional generated heat becomes part of the equilibrium state between molecular collisions and vibrations, plus the emission and
absorption of radiation.
Importantly, this helps formulate an explanation for viscous dissipation, and/or natural P-T system relationships
that being molecular collisions are generally not elastic therefore heat is readily given off, as well as Joule’s weight experiment.
The implication being that intermolecular collisions even in the condensed matter states are not necessarily elastic, as was previously
envisioned. This again is in agreement with both natural P-T system relationships and molecular viscous dissipation.
Furthermore it has been determined that collisions between photons and electrons are inelastic5,6,7,8. With that being the case then why would anyone even believe that collisions between molecules are anything but inelastic! This also bodes the question; to what degree are collisions between thermal radiation and condensed matter elastic?
Note the concept of inelastic collisions is at odds with Avogadros hypothesis, and the ideal gas law because these are based upon tradiational kinetic theory. In this author's new understanding of kinetic theory, since wall molecules tend to massive in comparision to small gas molecules i.e. montaoomic, diatomic, triatomic, then the walls impose thier kinematics onto these relatively small gas molecules, if the gas is sufficiently dilute. And this explains why such small gas molecules seemingly adhere to traditionally accepted kinetic theory.
Copyright Kent W. Mayhew
