I teach grade 12 physics and am about to introduce collisions. I am explaining that in elastic collisions, kinetic energy is conserved and in inelastic collisions, kinetic energy is not conserved. The kinetic energy in inelastic collisions can be lost to heat, sound and electromagnetic radiation.
As I think about it though, do heat, sound and light not also have kinetic energy? Heat is movement of particles which is kinetic energy. Sound is movement of air particles which is also kinetic energy. Lastly, if I am not mistaken, light (EMR) has a relativistic kinetic energy.
If you were to track every molecule and photon's kinetic energy after a collision, would kinetic energy be conserved in all collisions?
The only thing that makes me think it wouldn't would be somehow if the energy was converted into some form of potential energy. Like a collision where one object causes another object to increase in height therefore increasing the gravitational potential energy of the object.
Edit: Note, I am not teaching my students anything deeper than the basic macroscopic conception of collisions. While I was prepping, it just got me thinking about this.