A force in the opposite direction to the motion of an object will cause it to slow down or decelerate. This is because the force is working against the object's existing motion, effectively reducing its velocity.

Here's a breakdown:

* Force: A push or pull that can change an object's motion.

* Direction: The way a force acts (up, down, left, right, etc.).

* Motion: The movement of an object.

Examples:

* Friction: The force that opposes motion between surfaces in contact. When you push a box across the floor, friction acts in the opposite direction, slowing it down.

* Air resistance: The force that opposes the motion of an object through the air. When a ball is thrown upwards, air resistance slows it down as it rises.

* Brakes: When you apply brakes on a car, they create a force opposite to the car's motion, causing it to slow down.

Let me know if you have any other questions!