* Net Force: This is the overall force acting on an object. It's the sum of all forces acting on the object. If there's a net force, it will cause the object to accelerate, meaning its velocity will change.

* Example: Pushing a box across the floor. The force of your push, minus friction, creates a net force causing the box to accelerate and change its velocity.

* Friction: This force opposes motion and acts against the direction of movement. Friction can slow down an object, reducing its velocity.

* Example: A car rolling to a stop. Friction from the brakes and tires against the road causes the car to slow down.

Let me know if you'd like more examples or want to explore other forces!