Here's why:
* Speed is a scalar quantity, meaning it only has magnitude (how fast something is moving).
* Direction is also a scalar quantity, telling you where something is moving.
* Velocity is a vector quantity, combining both magnitude (speed) and direction.
Therefore, velocity fully describes the motion of an object. For example, saying "the car is traveling at 60 miles per hour" only gives the speed. Saying "the car is traveling at 60 miles per hour north" provides both speed and direction, giving the car's velocity.
