Final answer:
Momentum is conserved in all collisions, while kinetic energy is conserved only in elastic collisions.
Step-by-step explanation:
In the context of collisions, momentum is conserved when the total momentum of a system remains constant before and after the collision.
However, kinetic energy is only conserved in elastic collisions. In an elastic collision, both momentum and kinetic energy are conserved, meaning the total momentum and total kinetic energy of the system remains constant.
On the other hand, in inelastic collisions, kinetic energy is not conserved, but momentum is still conserved. In an inelastic collision, the objects involved stick together or deform upon collision, resulting in a loss of kinetic energy.
In summary, momentum is always conserved in all types of collisions, while kinetic energy is only conserved in elastic collisions.