In this answer it was stated that potential energy is a property of a system and not an individual particle.
If we have two particles (1 and 2) interacting via a conservative force, we can write an equation regarding the total energy of the system and its conservation:
KE1 + KE2 + PE(sys) = KE1' + KE2' + PE(sys)'
Where the ' indicates final.
I know this equation is incorrect, but my question is why is it incorrect?
I most definitely am interpreting this answer incorrectly.