Velocity of separation:

Therefore, during the small duration (t_c - t₁ ) while deformations are developed to its maximum value Δ_(max) ,

 (i)        Impulse of force on m₂ = m₂ (V_c - V₂)     

 (ii)       Impulse of force on m₁ = m₁ (V_c - V₁) =       

Furthermore, where the bodies undergo either fully elastic or partly elastic deformations, there is certain amount of recovery of the deformation and equivalent period of recovery = (t₂  - t_c ) . After this period is over, the two bodies get detached physically as illustrated in

Figure (d) at t = t₂ . If the final velocities of the two bodies are V₁′ and V₂′ , it may be understood from commonsense that

                                                              V₁′ < V_c  < V₁

while                                                     V₂′ > V_c  > V₂

and impulse on m₂

whereas impulse on m₁

After the instant t = t₂ ; mass m₂ shall move faster with respect to mass m₁ and therefore (V₂′ - V₁′) is termed as velocity of separation after the impact.