The orientation of velocity and acceleration that causes something to initially slow down is when they are opposite in direction.

Here's why:

* Velocity represents the direction and speed of an object's motion.

* Acceleration represents the rate of change of velocity.

If acceleration is in the opposite direction of velocity, it means the object is being slowed down. This is because the acceleration is working against the current motion, decreasing the speed.

Example:

Imagine a car moving to the right (positive velocity). If the brakes are applied (acceleration to the left, opposite direction), the car will slow down.

Let me know if you would like to discuss other scenarios!