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Please Take Out Your Homework

# Please Take Out Your Homework

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## Please Take Out Your Homework

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1. Please Take Out Your Homework

2. FRICTION Friction - a force that opposes motion, or “pushes back” when two surfaces are touching. It’s always around and it affects everything.

3. Without friction…

4. FRICTION- works against you …..but it can be helpful! When do I want… • A lot of friction? • http://www.youtube.com/watch?v=yTKwS-J7qVE • A little bit of friction? • http://digg.com/video/the-science-of-figure-skating • http://www.nbclearn.com/olympics

5. Friction types and parts… • There are three Basic Types of Friction • Static • Kinetic • Fluid

6. Types of friction: 1) Static friction: Friction that resists the initiation (start) of sliding motion between two objects at rest. Keeps things stopped

7. Types of friction: 2) Kinetic friction: The force that opposes the movement of two surfaces that are in contact and moving over each other.To make something move, you just overcome static friction by pulling with a force larger than kinetic friction.

8. Two types of Kinetic Friction: a) Sliding – the objects are sliding b)Rolling – the objects are rolling. Rolling is usually less than sliding.

9. Types of friction: 3) Fluid friction: The friction between layers of a fluid. 2 types- Liquid and Gas Liquid- water, oil etc. Gas - Air

10. Types of friction: Described by viscosity. Viscosity – the “thickness” of a fluid. Low viscosity = “thin;” High viscosity = “thick” or “viscous.” The less viscous a fluid is, the easier it moves.

11. Does Size Matter? I’m talking about Mass or surface area folks!

12. Friction DOES depend upon: 1. surface area in contact2. mass/gravity (weight) of object3. coefficient of friction – “mu”(the texture of the surface)

13. Friction is cumulative • Small amounts of friction in a system add up to become a large amount of friction.

14. Textbook friction…CHALLENGE