The acceleration of an object is 0 under the following conditions:

1. Constant Velocity:

   When an object moves at a constant velocity (both constant speed and constant direction), its acceleration is zero. Acceleration is defined as the rate of change of velocity. If the velocity isn't changing, there is no acceleration.

2. Object at Rest:

   When an object is at rest, its velocity is zero, and since it remains at zero, the rate of change of velocity is also zero. Therefore, its acceleration is zero.

3. Net Force of Zero:

   According to Newton's Second Law of Motion (F = ma), acceleration is directly proportional to the net force acting on an object and inversely proportional to its mass. If the net force acting on the object is zero, then the acceleration is also zero, regardless of the object's mass. This can occur when multiple forces are acting on the object, but they balance each other out.