It's a bit tricky, because both velocity and acceleration play a role in determining direction. Here's a breakdown:

* Velocity is a vector quantity, meaning it has both magnitude (speed) and direction. It tells you *where* something is going at a given instant.

* Acceleration is also a vector quantity. It tells you how the *velocity* is changing. This change can be in magnitude (speeding up or slowing down), direction (turning), or both.

Here's how they work together:

* Constant Velocity: If something moves with constant velocity, its direction doesn't change. This means its acceleration is either zero (no change in velocity) or it's perpendicular to the velocity (only changing the direction, not the speed). Think of a car moving in a straight line at a constant speed.

* Changing Velocity: If something's velocity changes, there's acceleration present. This change could be in speed (like a car speeding up), in direction (like a car turning), or both (like a car speeding up while turning).

In summary:

* Velocity directly determines the direction of motion *at a given instant*.

* Acceleration determines *how the direction of motion changes* over time.

Let me know if you'd like more examples!