Adding chains to tires in the winter time for better traction in the snow and ice
Adding Salt to and icy sidewalk
Adding oil to a car's engine
Using wheels on a cart
Using brakes to stop your bicycle.
Sliding across the rug and getting a rug burn on your leg.
Rubbing your hands together to keep them warm
Using the eraser on your pencil to correct your test mistake
Increased force is added to press the objects closer together.
Surfaces objects are smoother
Surfaces of the objects are rougher
Wheels are added to one of the objects in contact with the other.
Here's an interesting quiz for you.