Physics Weekly

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Chapter 9: Gravity
Marymount High School
a journey into the physical world!

Physics Syllabus

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Judith S. de Nuño
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Daily Lunch in the Science Patio
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Chapter Objectives

  • Explain Newton's idea of why the apple falls to Earth.
  • Explain why the moon does not fall to Earth.
  • Explain how Earth is falling.
  • State Newton's law of universal gravitation.
  • Explain the significance of an inverse-square law.
  • Explain the connection between gravitation and the idea that the universe may stop expanding and begin to contract.
  • Describe the gravitational field outside Earth.
  • Describe the gravitational field inside Earth.
  • Explain why an astronaut in Earth orbit seems weightless even though there is a gravitational force.
  • Explain ocean tides.
  • Give examples of tides other than those in water.
  • Describe black holes.

Chapter Terms:

  • law of universal gravitation
  • inverse-square law
  • weightlessness
  • spring tide
  • neap tide
  • gravitational field
  • black hole
  • Big Bang

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Chapter Formulas:


F =



Chapter Outline Framework:

  • The Universal Law of Gravity
  • The Universal Gravitational Constant, G
  • Gravity and Distance; The Inverse Square Law
  • Weight and Weightlessness
  • Ocean Tides
    • Tides in the Earth and Atmosphere
    • Tides on the Moon
  • Gravitational Fields
  • Gravitational Field Inside a Planet
  • Einstein's Theory of Gravitation
  • Black Holes
  • Universal Gravitation

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Animated Graphics Courtesy of
Jo's World