What is the relationship between elastic collisions and kinetic energy?
In real life, truly elastic collisions happen only when no contact takes place. Billiard balls are nearly elastic, but careful measurement would show that some kinetic energy is lost. The only collisions that qualify as truly elastic would interact thru near misses of bodies in which there is either
- gravitational attraction,
- attraction due to charge or magnetism, or
- repulsion due to charge or magnetism.
I hope this helps,