* Constant Acceleration: Constant acceleration means the velocity is changing at a steady rate. The direction of the acceleration determines whether the object is speeding up or slowing down.

* Zero Speed: Zero speed simply means the object is momentarily at rest.

Scenario:

Imagine a ball thrown straight up into the air.

* As the ball goes up: It has a positive upward velocity and a constant downward acceleration due to gravity.

* At the peak of its flight: The ball momentarily stops (speed is zero) before it starts falling back down. Even though the acceleration due to gravity is constant, the speed is zero at the peak.

In summary: Constant acceleration doesn't mean an object must always be moving. An object can have zero speed at a specific point in time while still experiencing constant acceleration.