RED SLIDE: These are notes that are very important and should be recorded in your Physics Notebook. Copyright © 2010 Ryan P. Murphy

RED SLIDE: These are notes that are very important and should be recorded in your science journal. BLACK SLIDE: Pay attention, follow directions, complete projects as described and answer required questions neatly. Copyright © 2010 Ryan P. Murphy

New mini area of focus: New mini area of focus:

New mini area of focus: Friction New mini area of focus: Friction

Friction: The resistance encountered when one object is moved in contact with another.

The four types of friction The four types of friction - Static - Static - Sliding - Sliding - Rolling - Rolling - Fluid - Fluid Copyright © 2010 Ryan P. Murphy

Static friction: Friction between two surfaces that are not moving past each other. Static friction: Friction between two surfaces that are not moving past each other. Copyright © 2010 Ryan P. Murphy

Sliding Friction: The force that opposes the motion of two surfaces sliding past each other. Sliding Friction: The force that opposes the motion of two surfaces sliding past each other. Copyright © 2010 Ryan P. Murphy

Sliding Friction: The force that opposes the motion of two surfaces sliding past each other. Sliding Friction: The force that opposes the motion of two surfaces sliding past each other. Copyright © 2010 Ryan P. Murphy

Sliding Friction: The force that opposes the motion of two surfaces sliding past each other. Sliding Friction: The force that opposes the motion of two surfaces sliding past each other. Copyright © 2010 Ryan P. Murphy

Video! Ice Storm (A world without Friction) –This is why you should not travel in an ice storm.

Rolling friction: The friction between a rolling object and the surface it rolls on. Rolling friction: The friction between a rolling object and the surface it rolls on. Copyright © 2010 Ryan P. Murphy

Only a small area is in contact.Only a small area is in contact. Copyright © 2010 Ryan P. Murphy

Which bike will be faster? Why?Which bike will be faster? Why? Copyright © 2010 Ryan P. Murphy

Which bike will be faster? Why? Where are we?Which bike will be faster? Why? Where are we? Copyright © 2010 Ryan P. Murphy

Which bike will be faster? Why?Which bike will be faster? Why? Copyright © 2010 Ryan P. Murphy

Which bike will be faster? Why?Which bike will be faster? Why? Copyright © 2010 Ryan P. Murphy Road bike Road bike Light weight Light weight Small thin tires = less friction, more aerodynamic Small thin tires = less friction, more aerodynamic

Which bike will be faster? Why?Which bike will be faster? Why? Copyright © 2010 Ryan P. Murphy Road bike Road bike Light weight Light weight Small thin tires = less friction, more aerodynamic Small thin tires = less friction, more aerodynamic Mountain bike Mountain bike Heavy / Durable Heavy / Durable Wide tire with lots of grip to increase friction. Wide tire with lots of grip to increase friction.

Fluid friction: When an object is moving in liquid or gas. Fluid friction: When an object is moving in liquid or gas. Copyright © 2010 Ryan P. Murphy

Video –Tillman the skateboarding, skimboarding, and surfing dog. –This is just relaxing for the next four minutes of our busy day. –Examples of Sliding, Rolling, and Fluid Friction. People standing around are static friction. –

Aerodynamic: Designed or arranged to offer the least resistance to fluid flow. Aerodynamic: Designed or arranged to offer the least resistance to fluid flow. Copyright © 2010 Ryan P. Murphy

Video (Optional) The worlds fastest bicycle and aerodynamics. –

The word drag refers to wind resistance. –(The force acted upon a moving object by the air or water)

The word drag refers to wind resistance. –(The force acted upon a moving object by the air or water)

The word drag refers to wind resistance. –(The force acted upon a moving object by the air or water)

The word drag refers to wind resistance. –(The force acted upon a moving object by the air or water)

Hydrodynamic: A shape designed to move efficiently through the water. Hydrodynamic: A shape designed to move efficiently through the water. Copyright © 2010 Ryan P. Murphy

“Why does a golf ball have dimples?”

A golf ball has dimples to make it more air resistant.

A golf ball has dimples to make it less resistant to the air. –Thus travel further and straighter.

A golf ball has dimples to make it less resistant to the air. –Thus travel further and straighter.

A golf ball has dimples to make it less resistant to the air. –Thus travel further and straighter. An object in motion stays in motion

No Dimples

Those large caps on trucks help decrease fluid friction with the air.

Aerodynamics: Learn more at…

Hurricane resistant building.

–This structure should survive massive wind force and high water.

Friction Friction Slows an object down until it stops Slows an object down until it stops Produces heat Produces heat Wears object down Wears object down Copyright © 2010 Ryan P. Murphy

Friction Friction Slows an object down until it stops Slows an object down until it stops Produces heat Produces heat Wears object down Wears object down Copyright © 2010 Ryan P. Murphy

Friction Friction Slows an object down until it stops Slows an object down until it stops Produces heat Produces heat Wears object down Wears object down Copyright © 2010 Ryan P. Murphy

Video (Optional) Making a Friction Fire. –

Friction Friction Slows an object down until it stops Slows an object down until it stops Produces heat Produces heat Wears object down Wears object down Copyright © 2010 Ryan P. Murphy

Friction Friction Slows an object down until it stops Slows an object down until it stops Produces heat Produces heat Wears object down Wears object down Copyright © 2010 Ryan P. Murphy

Activity! Examining the wear on your treads from friction. –Which parts of your shoe are most worn down? –Does this tell you anything about how you walk? Copyright © 2010 Ryan P. Murphy

Activity Simulator: Ramp and Friction p-forces-and-motionhttp://phet.colorado.edu/en/simulation/ram p-forces-and-motion

Copyright © 2010 Ryan P. Murphy How can you reduce friction when it’s unwanted?

Copyright © 2010 Ryan P. Murphy

Answer! Engine oil is very important to keep pistons lubricated. This reduces friction and thus heat which can expand metal and cause damage. Copyright © 2010 Ryan P. Murphy

There is no friction in space. A space vehicle will travel in the same direction at the same speed until….

acted upon by a force.

Heading this way for millions of years…? NEO’s Near Earth Objects. Heading this way for millions of years…? NEO’s Near Earth Objects.