Final answer:
In a collision between two objects of equal mass, when one object is at rest and the other is in motion, after the collision, the moving object comes to rest and its momentum is transferred to the previously stationary object which then moves with the same velocity. This scenario represents an inelastic collision where momentum is conserved but kinetic energy is not.
Step-by-step explanation:
Momentum Conservation in Collisions
When two objects of equal mass collide, the law of conservation of momentum states that the total momentum of the system remains constant if no external forces act on it. In the scenario where Object A is moving with a velocity of 15 m/s in the +X direction and object B is initially at rest, after the collision, Object A comes to rest, the momentum possessed by Object A is transferred to Object B. Object B must then move with the same velocity as Object A had before the collision, which is 15 m/s, but in the opposite direction to conserve momentum.
In terms of whether the collision is elastic or inelastic, since Object A stops completely and Object B moves away with the same velocity that Object A initially had, we can infer that the collision is an inelastic collision as the objects do not rebound off each other but rather transfer momentum. This results in momentum being conserved, but kinetic energy is not conserved as some of the kinetic energy is likely converted into other forms of energy such as heat, sound, or potential energy in deformations.