You're on the right track! Knowing both the speed and direction of an object while it's in motion gives you its velocity. However, knowing velocity alone doesn't tell you the acceleration.

Here's why:

* Velocity describes how fast an object is moving *and* in what direction.

* Acceleration is the rate at which an object's velocity changes.

Think of it like this:

* Constant velocity: A car driving at a steady 60 mph on a straight road has a constant velocity. It's not accelerating.

* Changing velocity: A car speeding up from 0 to 60 mph is accelerating. Its velocity is increasing.

* Changing direction: A car turning a corner at a constant speed is also accelerating. Even though its speed stays the same, its direction is changing, so its velocity is changing.

To determine if an object is accelerating, you need to know:

1. Its initial velocity: Where and how fast it was moving at the start.

2. Its final velocity: Where and how fast it's moving at some later point in time.

3. The time it took to change velocity: How long it took to go from its initial to final velocity.

With this information, you can calculate the acceleration using the formula:

Acceleration = (Final velocity - Initial velocity) / Time

In summary: Knowing the speed and direction (velocity) of an object only tells you its current state of motion. To determine if it's accelerating, you need to know how its velocity is changing over time.