* At rest: The object is stationary and not moving.
* Moving at a constant speed in a straight line: The object is in uniform motion, covering equal distances in equal intervals of time.
Important points to remember:
* Zero acceleration does not necessarily mean the object is at rest. It could be moving at a constant velocity.
* Constant velocity means both constant speed and constant direction. If the direction changes, even if the speed remains the same, the object is accelerating.
Here are some examples:
* A car parked in a driveway: The car is at rest and has zero acceleration.
* A plane cruising at a constant altitude and speed: The plane is moving at a constant velocity and has zero acceleration.
* A ball rolling down a perfectly smooth, horizontal surface: Assuming no friction, the ball will continue to roll at a constant speed in a straight line, with zero acceleration.
In summary, an object with zero acceleration is either stationary or moving at a constant velocity (constant speed and direction).
