* Speed tells you how fast you are moving, but it doesn't tell you the direction.

* Acceleration is the rate of change of velocity. It describes how quickly your speed or direction is changing.

* Momentum is a measure of an object's mass and velocity. It tells you how much force would be required to stop the object.

Velocity is the only property that combines both speed and direction.

For example:

* Saying you are traveling at 60 miles per hour describes your speed.

* Saying you are traveling at 60 miles per hour north describes your velocity.