1. Friction

2. Friction makes it possible: To walk Use wheeled vehicles Sit Hold books

3. Which is not something fiction helps you do? A.) Float in outer space. B.) Walk C.) Sit in a seat. D.) Hold things

4. Friction is a force that occurs when 2 surfaces oppose each other.

5. Friction is a force A.) True B.) False

6. Rub your hands together to produce friction.

7. Types of friction Static Sliding Rolling Fluid

8. Which is not a type of friction? A.) Static B.) Kinetic/Sliding C.) Slippery D.) Rolling E.) Fluid Which is not a kind of friction?

9. Static Friction that acts on something that is not moving Piano is held in place by static friction Static friction keeps you in your seat No heat or wear is generated

10. Sliding Force resulting when pushing or pulling an object over a surface. Moving day—pushing a box across the floor Heat and wear can result

11. Rolling Contact is reduced because of rollers or wheels or ball bearings. Skate boards have ball bearings in the wheels. A cart has wheels. Less heat and wear will result.

12. Fluid friction Resistance from a “ liquid ” or air. Stirring a thick batter Walking through water Olympic bike riders

13. The wheels on a car are an example of what type of friction? A.) Static B.) Sliding C.) Rolling D.) Fluid

14. A box sitting on a slope is an example of which type of friction? A.) Static B.) Rolling C.) Fluid D.) Sliding

15. Air resistance is what kind of friction? A.) Static B.) Sliding C.) Rolling D.) Fluid

16. Mu is the coefficient of friction. This depends on the two surfaces involved.

17. Typical values of Mu: Wood on wood.25-.5(no units) Glass on glass.9-1.0 Steel on steel.6 Steel on steel with oil.09 Rubber on dry pavement 1.0 Ski on snow.04 Teflon on teflon.04

18. Which of the following is true about Mu? A.) It is always the same number B.) It is the "Coefficient of friction" C.) It doesn't depend on the surfaces involved

19. Assignment: Name 2 sports where friction is helpful and needed. Explain Name 2 sports where friction is reduced for better performance. Explain

20. Reducing friction A smooth surface does demonstrate as much friction as a rough surface. A lubricant can be used to reduce friction.

21. You can get rid of friction by A.) making the surfaces rougher B.) using lubrication C.) there is nothing you can do to reduce friction

22. Which of the following are true about friction? A.) We couldn't live without it B.) It depends on the two surfaces C.) It can be a bad thing D.) All of the above E.) None of the above