The Law of Universal Gravitation

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The Law of Universal Gravitation
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The legend goes that Sir Isaac Newton developed
his theory when an apple fell on his head
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This made him think!
Could the apples motion be related to how the
moon moves?
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He found that the moon falls around the Earth
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What's up?
Center
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If the Earth Wasnt there, the moon would follow
a straight line path due to ??????
INERTIA
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So why is the moon attracted to the Earth? Is
the Earth attracted to the moon?
Gravity
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HUH?
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Everything with a mass is attracted to everything
else with a mass. The strength of the attraction
depends upon the size of the masses and the
distance between them.
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Copy this down!
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INVERSE SQUARE LAW

• Because distance is on the bottom of the
  fraction, by whatever factor distance changes,
  Fgrav will change by that same factor, inversely
  squared

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SOOOOOOOOO.

• The more massive the objects are, the bigger the
  Fgrav
• The more distance between the masses, the SMALLER
  the Fgrav
• The less distance between the masses, the BIGGER
  the Fgrav

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(No Transcript)
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Try some problems!

• If the distance is X1/5, Fgrav will be
  X___________
• If one Mass is X14, Fgrav will be X___________
• If one mass is X3 and the other is X2 and the
  distance is X3, Fgrav will be X___________

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2/3
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• How does Fgrav of the following planets compare?

Fgrav X 1/2
M
2M
2M
Fgrav X 2/9
Fgrav X1
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What is the Fgrav acting between the Earth
(m5.98X1024 kg) and a 70kg student if the
student is at sea level, 6.37 x 106 m from the
Earths center?
Remember, G6.67 X10-11
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Click on the link below to see the effect gravity
has on projectiles
http//galileoandeinstein.physics.virginia.edu/mor
e_stuff/Applets/newt/newtmtn.html
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Newton IS a cool dude afterall