Inspired by this question a normal extension would be to ask:
What is the minimum potential energy/mass required (to behave as a turning point) for an elastic collision between $2$ point particles $A$ and $B$ with velocity $v_A^{\mu}$ and $v_B^{\mu}$ in a relativistic classical mechanics? (Assume number of particles are conserved)
P.S: Do check the question on why a naive application of Total energy $\geq$ Potential Energy will not suffice.
