Acollision in which some kinetic energy is lost is a(n) collision. a collision in which the objects become one and move together is a(n) inelastic collision.

Explanation :

The interaction between the two particles is the collision. The collision is of two types :

In elastic collision, the momentum and the kinetic energy of a system remain conserved.

In an inelastic collision, the momentum remains conserved and the kinetic energy is not conserved. Some energy gets lost in the form of sound energy, heat energy etc.

In the inelastic collision, the objects become one and move together with the same velocity.

prolly a beacuse the momentuem the car has increases while going down hill