Here's why:
* Velocity is a measure of both speed and direction.
* Uniform velocity means the object is moving at a constant speed in a straight line.
* Acceleration is the rate of change of velocity. If velocity is not changing, there is no acceleration.
Think of it this way: If you're driving a car at a steady 60 mph on a straight highway, your speed and direction aren't changing, so you're not accelerating.