V1,f V2,f = - (m₁ — m²)v₁,i + 2m2v2,i m1 + m2 (m2 — m₁)v2,i + 2m₁V1,i - m1 + m2 (7) (8) For inelastic collisions, energy conservation [or Eq. (6)] does not apply. In general, momentum conservation [or Eq. (5)] itself cannot determine the two final velocities without more details be- ing given. However, there is a special case called a completely inelastic collision, in which the two objects stick together and move as one object after the collision. The two objects thus have the same final velocity, V₁₁f = V2,f = Vf. Combining this relation and Eq. (5), one obtains Vƒ m1v1,i+m2v2,i m1 + m2 (9)

V1,f V2,f = - (m₁ — m²)v₁,i + 2m2v2,i m1 + m2 (m2 — m₁)v2,i + 2m₁V1,i - m1 + m2 (7) (8) For inelastic collisions, energy conservation [or Eq. (6)] does not apply. In general, momentum conservation [or Eq. (5)] itself cannot determine the two final velocities without more details be- ing given. However, there is a special case called a completely inelastic collision, in which the two objects stick together and move as one object after the collision. The two objects thus have the same final velocity, V₁₁f = V2,f = Vf. Combining this relation and Eq. (5), one obtains Vƒ m1v1,i+m2v2,i m1 + m2 (9)