PLEASE TAKE OUT YOUR HOMEWORK FRICTION Friction a

PLEASE TAKE OUT YOUR HOMEWORK

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

WITHOUT FRICTION…

FRICTION- WORKS AGAINST YOU …. . BUT IT CAN BE HELPFUL! WHEN DO I WANT… A lot of friction? http: //www. youtube. com/watch? v=y. TKw. S-J 7 q. VE A little bit of friction? http: //digg. com/video/the-science-of-figure-skating http: //www. nbclearn. com/olympics

FRICTION TYPES AND PARTS… There are three Basic Types of Friction Static Kinetic Fluid

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

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.

TWO TYPES OF KINETIC FRICTION: a) Sliding – the objects are sliding b) Rolling – the objects are rolling. Rolling is usually less than sliding.

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

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.

DOES SIZE MATTER? I’M TALKING ABOUT MASS OR SURFACE AREA FOLKS!

Friction DOES depend upon: 1. surface area in contact 2. mass/gravity (weight) of object 3. coefficient of friction – “mu”(the texture of the surface)

FRICTION IS CUMULATIVE Small amounts of friction in a system add up to become a large amount of friction.

TEXTBOOK FRICTION…CHALLENGE