Fundamentals of physics

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Fundamentals of physics
Mechanics
Unit 5 Motion and Forces 5.4 Friction ...
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Fundamentals of physics - Mechanics

• Friction
• --------------------------------------------------
  --------------------------------------

• Force of friction acts when surfaces slide or
  tend to slide over one another. Irregularities on
  the surfaces in contact causes friction
• The amount of friction depends on the materials
  and the force pressing them together.
• All surfaces have microscopic irregularities that
  obstruct motion even those which seem to be very
  smooth.
• At many points of contact the atoms cling
  together.
• Also when one slides over each other another,
  the objects must rise over the microscopic bumps
  or scrape off the offending atoms.

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Fundamentals of physics - Mechanics

• Friction
• --------------------------------------------------
  --------------------------------------

• The direction of the force of friction always
  opposes the direction of motion.
• If the crate is pushed to the right, then the
  friction acts toward the left.
• The stone falls downward, and air resistance
  (friction) acts upward .

Walking in water presents a resistance to our
motion (friction)
Air Resistance
Push
Friction
Weight
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Fundamentals of physics - Mechanics

• Friction
• --------------------------------------------------
  --------------------------------------

• Friction does not depend on the area of contact.
  
• So those extra wide tires you see on some cars
  provide no more friction than narrower tires.
• Give examples of friction that is useful to us
  and those that cause problems.

So those extra wide tires you see on some cars
provide no more friction than narrower ones
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Fundamentals of physics - Mechanics

• Friction
• --------------------------------------------------
  --------------------------------------

• Summary of Terms
• Friction - The resistive force that opposes the
  motion or attempted motion of an object when
  surfaces are in contact either with another
  object or through a fluid.

Attempted motion
Friction
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End of Unit Unit 5 Motion and Forces5.4
Friction...