The phrase "rocket had a velocity of 50m" is incomplete because it lacks a unit of measurement for the velocity. Here's why:

* Velocity requires both magnitude and direction: Velocity describes how fast something is moving *and* in what direction.

* "50m" only indicates distance: The phrase only specifies a distance (50 meters), not the rate at which the rocket is traveling.

To complete the phrase, we need a unit of time:

Correct Example: The rocket had a velocity of 50 meters per second (50 m/s).

Now we know the rocket is traveling 50 meters every second.