Newton

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Newtons Three Laws
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IQ 12/16/13page 70

• Why does a bowling ball eventually stop when you
  throw it down the lane? Explain using scientific
  terms.

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Athletes use spinning, pushing and bumping
motions to score points.

• Can you think of some examples?

Soccer
Football
Track
Basketball
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Newtons First Law of Motion

• An object at rest remains at rest unless acted on
  by an unbalanced force.
• An object in motion continues in motion with the
  same speed and direction unless acted upon by an
  unbalanced force.
• This law is often called the law of inertia".

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What does inertia mean?

• Objects tend to keep on doing what they're doing.
  
• Inertia depends on the mass of the object.
• The more massive the object, the more it resists
  changes in its motion.

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Real World Examples

• Soccer
• If I kick a soccer ball towards the net and the
  goalie is not there to stop it
• GOAL!!!

• Bowling
• When I roll the bowling ball down the lane, it
  will keep going until it hits the pins or the
  gutter!

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How can I describe a magic trick in terms of
forces?

• Materials
• Cup
• Playing card
• Coin
• Create a hypothesis
• Suppose you were to flick the card, sending it
  flying horizontally. What would happen to the
  coin? Why?
• Suppose you were to slowly pull the card
  horizontally from the mouth of the cup. What
  would happen to the coin? Why?
• Conclusions
• 3) Which forces acted on the coin before the card
  moved?
• 4) Which forces acted on the card as it moved?
• 5) Using Newtons Laws of Motion, explain what
  happened to the coin when the card was flicked.

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• Conclusions
• 3) Which forces acted on the coin before the card
  moved?
• 4) Which forces acted on the card as it moved?
• 5) Using Newtons Laws of Motion, explain what
  happened to the coin when the card was flicked.

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How do magicians perform the tablecloth trick?
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IQ 12/17/13pg 72

• Would it take more force to push a car or a bike?
  Why? Explain

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Newtons Second Law of Motion

• Acceleration (change in speed or direction) is
  produced when a force acts on a mass. The greater
  the mass (of the object being accelerated) the
  greater the amount of force needed (to accelerate
  the object).

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Which situation would require most force?

• Heavy shopping cart vs. empty shopping cart
• Stopping a person on a bike vs. catching a
  basketball
• Kicking a tennis ball and kicking a bowling ball
• Pushing a 40 kg box vs. pushing a 1 kg box

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• More mass-more force to move object
• Less mass-less force to move object

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What does the 2nd law mean?

• Heavier objects require more force to move the
  same distance as lighter objects.

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Real World Examples

• If you are a defensive lineman, who would be
  easier to tackle
• A running back that weighs 100 pounds or a
  running back that weighs 300 pounds?

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IQ 12/18/13pg74

• Which one of Newtons Laws is the relationship
  between amount of force needed to accelerate an
  objects mass?

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Newtons Third Law of Motion

• For every action there is an equal and opposite
  re-action.
• If one object exerts a force on another object,
  then the second object exerts a force of equal
  strength in the opposite direction on the first
  object.

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• Action and reaction forces in a pair do not act
  on the same object, otherwise nothing would move.
  

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Equal but Opposite
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What does this mean?

• This means that for every force there is a
  reaction force that is equal in size, but
  opposite in direction. That is to say that
  whenever an object pushes another object it gets
  pushed back in the opposite direction equally
  hard.

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In the Real World

• Golf
• When Tiger Woods hits the golf ballwhat is the
  reaction?
• Racing
• When Dale Earnhardt steps on the gas pedal, what
  is the reaction?

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Ex. swimming
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Ex. Running
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Your Task Choose one of the following

• Write a paragraph to explain an example of each
  of Newtons 3 Laws
• OR, Draw a picture to illustrate each of Newtons
  3 Laws

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• Now that Ive given you a few examples, I want
  you to think of one example of each of Newtons
  Three Laws of Motion from sports.

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Conservation of Momentum