When the acceleration and velocity vectors are pointing in opposite directions, the object is slowing down.

Here's why:

* Velocity tells you the direction and speed of an object.

* Acceleration tells you how the velocity is changing.

If acceleration is in the opposite direction of velocity, it means the velocity is decreasing. Think of it like this:

* You are driving forward (positive velocity).

* You apply the brakes (negative acceleration).

* Your car slows down.

This is often referred to as deceleration.