The change in velocity is the difference between the final velocity and the initial velocity. It can be calculated using the following equation:

```

Change in velocity = Final velocity - Initial velocity

```

The change in velocity is a vector quantity, which means that it has both magnitude and direction. The magnitude of the change in velocity is the difference between the speeds of the object at the final and initial times, and the direction of the change in velocity is the direction of the final velocity minus the direction of the initial velocity.

For example, if an object starts at rest and accelerates to a velocity of 10 m/s in the positive x-direction, then the change in velocity is 10 m/s in the positive x-direction. If an object is moving at a velocity of 10 m/s in the positive x-direction and then slows down to a velocity of 5 m/s in the positive x-direction, then the change in velocity is -5 m/s in the positive x-direction.