Chapter 8, Problem 79PP

The Global Positioning System (GPS) uses a “constellation’" of some 30 satellites to provide accurate positioning for any point on Earth (Fig. 8.19). GPS receivers time radio signals traveling at the speed of light from three of the satellites to find the receiver’s position. Signals from one or more additional satellites provide corrections, eliminating the need for high-accuracy clocks in individual GPS receivers. GPS satellites are in circular orbits at 20,200 km altitude.

FIGURE 8.19 GPS satellites (Passage Problems 72-75)

The current generation of GPS satellites has masses of 844 kg. What’s the approximate total energy of such a satellite?

1. a. 6 GJ
2. b. 3 GJ
3. c. −3 GJ
4. d. −6 GJ
5. e. −8 GJ