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CHAPTER
Gravitation 9
CONCEPTS IN CONTEXT
Concepts
in
Context Hundreds of artificial satellites have been placed in orbit around the Earth,
such as this Syncom communications satellite shown just after launch 9.1 Newton’s Law of Universal
from the Space Shuttle. Gravitation
With the concepts we will develop in this chapter, we can answer 9.2 The Measurement of G
various questions about artificial satellites:
9.3 Circular Orbits
? Communications satellites and weather satellites are placed in high- 9.4 Elliptical Orbits; Kepler’s Laws
altitude “geosynchronous” orbits that permit them to keep in step
9.5 Energy in Orbital Motion
with the rotation of the Earth, so the satellite always remains at a
fixed point above the equator. What is the radius of such a geosyn-
chronous orbit? (Example 6, page 279; and Physics in Practice:
Communications Satellites and Weather Satellites, page 281)
? Surveillance satellites and spacecraft such as the Space Shuttle usually
operate in low-altitude orbits, just above the Earth’s atmosphere. How
quickly does such a satellite circle the Earth? (Example 7, page 280)
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