Understanding Acceleration and Velocity
* Velocity: Describes how fast an object is moving and in what direction. It's a vector quantity (magnitude and direction).
* Acceleration: Describes the rate of change of velocity. It's also a vector quantity.
Zero Acceleration, Non-Zero Velocity
An object has zero acceleration when its velocity is *not changing*. This means the object is moving at a constant speed in a constant direction.
Examples
1. A Car Traveling at a Constant Speed: A car cruising down a straight highway at 60 mph has a constant velocity. Since its velocity isn't changing, its acceleration is zero.
2. A Ball Rolling on a Flat Surface: A ball rolling across a flat surface with no friction will continue to roll at a constant speed and direction. It has zero acceleration.
3. A Satellite in Orbit: A satellite in a stable orbit around Earth is constantly moving, but its speed and direction remain relatively constant. Its acceleration is due to gravity, but it's constantly being balanced out by the satellite's motion, resulting in a near-zero net acceleration.
Key Point: Zero acceleration *doesn't* mean the object is stationary. It means the object's velocity is not changing.
