Friction

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Chapter 3.3

• Friction

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Question 1

• Friction is resistance force.
• Friction is defined as the force that opposes the
  sliding or rolling motion of two surfaces that
  are in contact.

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Question 2

• The two factors that friction is dependent upon
  are
• the composition of the materials
• the roughness of the surfaces of the materials

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A CLOSER LOOK SANDPAPER

• Friction is caused by the irregularities in the
  surfaces of objects that are touching.
• Even very smooth surfaces have microscopic
  irregularities that
• obstruct motion.

The rougher the surface, the ______________ the
friction.
greater
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Question 3

• Friction increases when the two surfaces pushed
  together with more force. This increases the
  strength of the microwelds.
• Friction can also increase as the roughness of
  the surfaces increases.

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Question 4

• Static friction (prevents two surfaces in contact
  from sliding or rolling past each other)
• Sliding friction (force acts in the opposite
  direction to the motion of the object causing it
  to slow down)
• Rolling friction (force resists rolling causing
  it to slow down--similar to sliding but usually
  much less than sliding)

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HOW DOES THE SURFACE INFLUENCE FRICTION?
sliding
sliding
rolling
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WHICH TYPE OF FRICTION?
rolling
sliding
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WHICH TYPE OF FRICTION?
sliding
rolling
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Question 5

• For objects at rest, the applied force must be
  strong enough to break the microwelds. After the
  microwelds are broken, the object requires less
  force to overcome sliding friction.
  http//www.regentsprep.org/regents/physics/phys01/
  friction/default.htm