Friction is a force that ____________ motion. This means it works against the motion and slows or stops objects. Friction is also the reason we can hold a pencil, sit in a chair, and ice skate.
We can use our understanding of how friction works in different ways. The surface along
which we travel tells us a lot about the amount of friction we will experience. A ___________ surface, like ice, allows us to move more freely. There is less friction between us and the surface, so we don’t slow down as quickly. Other surfaces such as soil, rocks, grass, and rugged asphalt are __________ and provide a greater amount of friction. Rough surfaces slow us down more quickly. If we understand the ____________ of our materials, we can build and design technology to help us move more efficiently.
Because we live on Earth, we experience friction everywhere. Pilots of aircrafts and space
shuttles must account for ___________________ , a type of friction experienced as we move through the air. Captains of watercrafts and submarines must account for _________, a type of friction experienced in water, as they move through rivers, lakes, and oceans.
_____________ can be a force we work with or work against. Imagine yourself on a roller coaster. You want to be able to move down the track quickly, especially during the drops, but you also want the brakes to bring your cart to a stop when the ride is over. Understanding when to increase or decrease friction is central to this technology!