Forces

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Forces Friction

• Chapter 10.1 and 10.2

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FORCE NET FORCE

• FORCE is a push or pull on an object
• Described by the magnitude and direction in
  which it acts.
• SI Unit Newton
• NET FORCE is the total/cumulative force on an
  object (add the two forces)

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Unbalanced Balanced Forces

• Unbalanced Force
• Causes an object to stop moving or change
  direction.
• Result in a net force and cause a change in the
  objects velocity (motion)
• Balanced Force
• Forces in equal magnitude opposite direction.
• No movement / No change in velocity

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What is the Net Force for the red airplane? ?
Why are these examples of unbalanced forces?
What is the Net Force for the green speed racer?
?
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Can you see the unbalanced force here?
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BRAIN BREAK!

• With your partner, discuss how balanced and
  unbalanced forces can apply to an arm wrestling
  match.

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FRICTION

• FRICTION is a force that two surfaces exert on
  each other when they rub against each other
• Forces act in OPPOSITE directions to each other!
• The strength of friction depends on
• 1) the type of surface
• 2) how hard the surfaces push each other.

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Types of Friction

• 1) Static Friction (Strongest)
• Acts on objects that are not moving. Works in
  opposite direction to intended motion.
• 2) Sliding Friction
• Occurs when two solid surfaces slide over each
  other.
• 3) Rolling Friction
• Occurs when an object rolls over a surface.
  Works in direction opposite to intended motion.
• 4) Fluid Friction (Weakest)
• Occurs when a solid object moves through a fluid
  (water, air, oil)

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What kind of Friction?
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What kind of friction?
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What kind of friction?
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Which type of hockey has more friction?
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Which skater will experience the most
friction? Hint Who exerts more downward force?