Elastic or Inelastic

In all three examples above, both momentum and energy are conserved. This is always the case. A collision where the total kinetic energy before and after the interaction is the same is called an elastic collision. Where there is a gain or loss of kinetic energy as a result of the interaction the collision is called inelastic.

in an elastic collision: momentum, kinetic energy and total energy are conserved in an inelastic collision: momentum and total energy are conserved, but the amount of kinetic energy changes

Of the examples given, only the second is an elastic collision.