Agenda for Oct 31 and Homework Due Nov 2

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Please consider these released STAR test questions:

A communication satellite is in a circular orbit around Earth. If the speed of the satellite is constant, the force acting on the satellite

1. is zero.
2. is decreasing.
3. points toward the center of Earth at all times.
4. points in the direction that the satellite is moving.

A satellite that is moving in a circular orbit around Earth and maintaining a constant speed will experience a

1. changing gravitational force toward Earth.
2. net gravitational force toward Earth.
3. changing acceleration away from Earth.
4. net acceleration away from Earth.

Agenda

• return homework harvest from chapter 6
• finish calculations for circular motion
  
  • lab
    discussion of lab
• Introduction to Universal Gravitation
  
  • Standing on the Shoulders of Giants
  • Galileo
  • Copernicus
  • Tycho Brahe
  • Johannes Kepler
    
    • Kepler's 1st law
      
      • the paths of the planets are ellipses, with the Sun at one focus.
    • Kepler's 2nd law
      
      • an imaginary line from the Sun to a planet sweeps out equal areas in equal time intervals.
      • 
    • Kepler's 3rd law
• • The squared quantity of the period, T_A, of object A divided by the period, T_B, of object B, is equal to the cubed quantity of object A’s average distance from the Sun, r_A, divided by object B’s average distance from the Sun, r_B.
    

    

• Isaac Newton
  
  • Newton's Law of Universal Gravitation
    
    • The gravitational force is equal to the universal gravitational constant, times the mass of object 1, times the mass of object 2, divided by the distance between the centers of the objects, squared.
    • 
    • mathematical relationships
    • direct (linear) with masses
    • inverse square with radius (distance)

Quickie Quiz

Homework

• Ch. 7, Read pp. 171-183 (stop at Two Kinds of Mass)
• Do problems:
  
  • p. 178 #7, 9
  • p. 185 #18
  • p. 191 #46, 47, 55