Friction

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Friction
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What factors affect friction?

• Types of surfaces
• How hard the surfaces are pushed together

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Types of Surfaces

• Smoother the surface- smaller the friction
• Examples of smooth surfaces
• ?
• ?
• ?
• The rougher the surface- greater the friction
• Examples

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What happens when we change a surface?

• How does adding rubber to the bottom of an object
  change the friction?
• What happens when the gym floor is dusty?
• How are other ways a surface changes the friction?

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Types of Friction

• Sliding
• Two solid surfaces slide over each other
• Direction of motion is OPPOSITE that of friction
• Examples
• Static
• Objects that arent moving
• Think about trying to push something that just
  wont move
• examples

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Types contd

• Rolling
• When an object rolls across a surface
• Easier to overcome than sliding friction
• Think about pushing a bike, is it easier or
  harder if the wheels are locked?
• Fluid
• When a solid object moves through a fluid
• Easier to overcome than sliding (think about an
  icy sidewalk ? )

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Real life examples of friction
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How hard the surfaces are pushed together

• What does this really mean?
• What are real world examples of pushing surfaces
  together to increase friction?

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How Does Friction Work?
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What is friction?

• Friction is one of the most significant phenomena
  in the physical world
• Surface resistance to relative motion the
  rubbing of the surface of one body against that
  of another
• Leonardo Da Vinci (1452-1519)
• was one of the first scholars to
• study friction systematically.

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What is friction

• Force is so fundamental that it defies full
  explanation, and compared to force, friction is
  relatively easy to identify
• Friction plays a part in the total force that
  must be opposed in order for movement to take
  place in many situations
• Weight is another term for gravitational force
  and is an important factor in friction

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Force to do friction

• EQUATION
• FµNµmg
• ? Where µ is the coefficient of friction (either
  static or kinetic), and N is the normal force. On
  a horizontal plane, the normal force is just the
  weight of the object, which is mg.

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A Powerful Force

• Friction can prove to be a very powerful force
  even when dealing with small scale objects.
• Ex Phone Book Friction Video

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Friction in Everyday Life

• Driving a car The force of friction encompasses
  the entire operation of a car and makes the tires
  possible to turn on the road. Tires are designed
  with a degree of tread that helps maintain a high
  degree of friction to allow the tire to grip
  tightly to the road and keep control. If there
  was no tread, there would be no friction and the
  car would not be able to stop at the appropriate
  time.

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Friction in Everyday Life

• Lighting a match This has to do with friction
  because as you strike a match to be lit, friction
  creates enough heat to ignite a chemical compound
  in the match head that allows the rest of the
  match to continue to burn.

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Friction in Everyday Life

• Using your computers mouse pad Friction occurs
  between the mouse and the desktop or mouse pad.
  Friction is required to move the mouse and have
  it respond appropriately. If you were to use a
  different kind of material for a mouse pad, such
  as a piece of sand paper, the mouse is harder to
  move. The piece of sand paper has more friction
  than the mouse pad.

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Friction in everyday life

• If we lived in a world with no friction, things
  may be a bit more chaotic. Automobiles, airplanes
  and other vehicles would have a tough time trying
  to slow down or stop because they would be trying
  to brake on a frictionless surface. This would be
  like trying to stop on an ice skating rink. There
  would be nothing to grip to the surface.
• Doing actions as simple as walking, writing, and
  eating would be impossible. Everything would be
  sliding around, never staying put. This could get
  very dangerous when we think about large bodies
  of water, or enormous structures not staying in
  place because we lived in a frictionless world.
• Gravity would become the defining force.

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Bibliography

• http//dictionary.reference.com/browse/friction?s
  t
• http//www.scienceclarified.com/everyday/Real-Life
  -Chemistry-Vol-3-Physics-Vol-1/Friction.html
• http//www.scienceclarified.com/everyday/Real-Life
  -Chemistry-Vol-3-Physics-Vol-1/Friction-Real-life-
  applications.html
• http//www.articlesbase.com/k-12-education-article
  s/friction-for-children-4-tricks-to-help-children-
  understand-friction-1416598.html
• http//www.nano-world.org/frictionmodule/content/0
  200makroreibung/0400historisch/0100leonardo/?lang
  en - Da Vinci
• http//www.school-for-champions.com/science/fricti
  on.htm - Friction Force
• http//www.youtube.com/watch?vhOt-D_ee-JE -
  Video
• http//ffden-2.phys.uaf.edu/211_fall2002.web.dir/b
  en_townsend/staticandkineticfriction.htm - Car
  Image
• http//en.wikipedia.org/wiki/FileTire_tread.jpg
  - Tire Tread
• http//jdaya15.wordpress.com/best-works/science-m/
  friction - Match
• http//www.cafepress.com/physfriction.31346452 -
  Mouse Pad