Final answer:
The momentum of Neo and Morpheus is nonzero because they have gained velocity, and momentum is a product of mass and velocity. Since they are in motion, they possess momentum, implying that there is a net force applied if their momentum changes over time.
Step-by-step explanation:
When Neo and Morpheus gain velocity (assuming it is not equal to zero), that implies they are in motion and therefore have momentum. The momentum of an object is a product of its mass and velocity. When an object has velocity, it also has direction, making momentum a vector quantity. Having gained a velocity means the momentum of Neo and Morpheus is now nonzero. This is aligned with the law of conservation of momentum, which states that momentum is conserved when no net external force acts on the system. However, if the momentum of the objects increases over time, it indicates that a net force is being applied (net force is equal to the rate of change of momentum).