1. Chapter 5.2 Friction at the Sochi Winter Olympics

2. Friction friction is the force that opposes motion.

3. Causes of friction Surfaces have tiny hills and valleys on both sides. As the surfaces slide across each other the hills and valleys grind against each other.

4. Causes of friction Friction depends on both surfaces. http://news.discovery.com/adventure/videos/science-friction-all-about-the-physics-of-curling-video.htm

5. Types of Friction Static friction - friction force that resists motion between surfaces that are not moving.

6. Types of Friction Sliding friction - the friction force that resists the motion of an object moving across a surface.

7. Types of Friction rolling friction - opposes motion of a rolling object.

8. Types of Friction air friction - a force of the surrounding fluid (air) working against motion

9. Types of Friction

10. Motion through water - viscous friction works much like air friction.

11. Effect of weight on friction Adding weight to a sliding or rolling object adds friction between the two surfaces. Which takes more force to push?

12. Decreasing Friction 1. Lubrication - such as oil 2. ballbearings 3. Magnetic Levitation

13. Increasing Friction 1. cleats

14. Increasing Friction 2. Race tires vs Street Tires - Street Tires increased friction in wet conditions. - Race tires increased friction on dry roads.