What is FRICTION

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					What is
FRICTION?
The Force of Friction – What is It?
Friction can prevent motion
  If an object is not moving and a force attempts to slide it
  across a surface, the force of friction will also act on the
  object.
   Friction between the object and the surface tries to keep the
  object from moving.
  This is one effect of friction, to stop objects from slipping.
Friction can oppose motion
  If one object is sliding across another, the force of friction will
  always try to stop this slipping.
  The force of friction acts in the direction opposite to the
  direction in which the object moves.
  Friction will either slow down the object, or make it more
  difficult for other forces to keep the object moving.
Friction can create motion
There are certain times when friction stops
slipping from taking place but actually creates
motion!
Friction prevents car tires from slipping. Without
the friction between your car tires and the road,
the tires would slip and the car would not move.
That is why schools are closed when it is icy.
Think about what might happen when bus tires
try to move on slippery roads!
    This is an example of friction creating motion.
When friction causes an object to move we
usually call it a traction force. But remember
traction is really friction.
The amount of Friction depends on…
 Texture of the two contact surfaces
   What are types of surfaces?
   What types would cause more friction?
 How hard the two surfaces are pressed together
   What variable might contribute to how hard they are
   pressed together?
   How will friction change with increased pressure?
How does FRICTION affect energy
transfer?
 The force of friction does WORK
 Friction transforms KE of a moving object(s) into
 HE
   Think of a time this is a desired outcome…
 Friction can also transfer energy to an object
   Tires are designed to maximize friction in order for a
   car to gain KE.
What factors can you think of
that might influence the force
       of FRICTION?