Chapter 2 Gravitation and the Waltz of the Planets

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Chapter 2Gravitation and the Waltz of the
Planets
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The Hot Debate!

• A ____________cosmology is a theory that proposes
  Earth to be at the center of the universe.
• versus
• A ____________cosmology is a theory that proposes
  the Sun to be at the center of the universe.

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Aristotles Model of geo-centric solar system
(384-322 BC)
But model couldnt account fully for
______________ of the planet!!!
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Retrograde Motion
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___________ Geo-centric Solar System
Tried to account for retrograde motion, but
could not quite match observations
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__________ devised the first comprehensive
helio-centric cosmology to successfully explain
retrograde motion
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Tycho Brahes Nose
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Mathematician ___________________ created laws of
planetary motion that describe the orbital
shapes, changing speeds, and the lengths of
planetary years
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Keplers First Law The orbit of a planet about
the Sun is an ______ with the Sun at one _____.
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The distance between the two foci impact the
eccentricity (e) of the ellipses shape.
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Keplers Second Law A line joining a planet and
the Sun sweeps out equal _____ in equal intervals
of ___.
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Keplers Third Law
The square of the ________ of revolution is
proportional to the cube of the ___________ of
the ellipse p2 ? a3
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Summary of Keplers Laws of Planetary Motion
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Italian scientist __________ made discoveries
that strongly supported a helio-centric cosmology
I do not feel obliged to believe that the
samegod who has endowed us with sense, reason
andintellect has intended us to forgo their
use. - Galileo
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Galileos telescope revealed all _______ of Venus
which could only occur IF Venus orbits the Sun.
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Galileos telescope revealed that Jupiter
had______ which orbited Jupiter instead
of__________.
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Geo-centric or Helio-centric?

• Galileo Ptolemy
• Kepler Copernicus
• Aristotle

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Sir Isaac Newton
What goes up, must come down!
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Newtons Universal Law of Gravitation

• Every body that has _______ has _______
• The gravity between the two bodies ________ with
  the mass
• The gravity between the two bodies
  ___________________

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Mass vs. Weight

• ________ is a measure of the total amount of
  material in the object
• ?
• ______ is the ____ with which an object is
• pulled down while on the ground (due to
  gravitys attraction)
• ?