:the solar system

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the solar system
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Engagement
Motion? How do you know?
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Flick the marble so it zooms off the table
Engagement

• How would you describe this motion?

?
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Flick the marble so it zooms off the table
Engagement

• Notice the marble rolls in a straight line.

?
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Losing your marbles yet?
Exploration

• Materials per person
• 1- Ping pong ball
• 1- marble
• 1- funnel
• with block stand

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Exploration
Ping-pong ball, marble and funnel
1. Place the ping-pong ball in the bottom of the
funnel 2. Predict what will happen if you
release a marble just inside the edge of the
funnel. 3. Did the marble behave as you
predicted?
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Challenge Keep marble from touching ping pong
ball
Exploration
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Exploration
What are the forces on the marble?
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Earth pulls down on the marble
Explanation
force due to gravity
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The funnel pushes on the marble
Explanation
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These two forces add together.
Explanation
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To give you the net force
Explanation
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Net ?
Explanation

• Gross income (3000/month)
• Minus
• taxes, insurance, membership dues, retirement,
  college savings, etc (560/month)
• Plus
• performance bonus (100/month)
• Equals
• Net Income (2540/month)

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Tug of War and Net Force
Explanation

• Which way does the flag move?

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The net force causes the marble to fall
(accelerate) toward the ball
Explanation

• Model the direction of the net force with your
  funnel and your hand

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The net force causes the marble to fall
(accelerate) toward the ball
Explanation

• Model the direction of the net force with your
  funnel and your hand

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Challenge Keep the marble from touching
the ping pong ball
Engagement
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How is the motion of the marble different now
from when you didnt move the funnel?
Exploration

• moving the funnel and base

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Explanation

• moving the funnel and base

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Successfully orbiting our marble
Explanation
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What does orbit mean?
Explanation

• Working definition?

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What does orbit mean?
Explanation

• Formal definition the actual or imaginary
  path taken by an object in its periodic motion
  around another object

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Explanation

• moving the funnel and base

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What forces are acting on the marble as it
orbits?
Explanation

• moving the funnel and base

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Earth still pulls on the marble
Explanation
force due to gravity same as before

• moving the funnel and base

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The funnel now pushes harder on the marble.
Explanation
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These two forces add together
Explanation
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to give you the net force.
Explanation
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to give you the net force.
Explanation
Model the direction of the net force with
your funnel and your hand
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to give you the net force.
Explanation
Model the direction of the net force with
your funnel and your hand
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The same forces act when the ball is on the other
side.
Explanation
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The net force on the marble always points toward
the center.
Explanation
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The net force on the marble always points toward
the center.
Explanation

• Can you model the direction of the net force
  with your hand?

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Center-tending force Centripetal force
Explanation

• Centripetal Force is required to keep an
  object moving in a circular path

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Marbles and funnels demonstrate centripetal force
and circular motion
Explanation
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Planets in our solar system orbit the sun
Explanation

• Similar to the marble orbiting the ping pong ball
  but not identical
• Gravity is the centripetal force keeping Earth in
  orbit.
• What are three things wrong with our model of the
  Earth orbiting the Sun?