1. What must be the orbital speed of a satellite in a circular orbit 780 km above the surface of the earth? RE = 6.38 × 106 m, mE = 5.97 × 1024 kg, and G = 6.674 × 10−11 Nm2/kg2. A. 10.23 km/s
B. 7.46 km/s
C. 6.56 km/s
D. 8.97 km/s

2. In order to be available all the time, a communications satellite must orbit in a circle above the equator and must remain above the same point on the earth’s surface. How long does it take for a communications satellite to make one complete orbit around the earth? RE = 6.38 × 106 m, mE = 5.97 × 1024 kg, and G = 6.674 × 10−11 Nm2/kg2.

A. 864,000 s
B. 0.864 s
C. 86,400 s
D. 8,640 s

3. Two moons orbit in a circular path around the same planet. The first moon has an orbital radius of r and the second has an orbital radius of R, where r < R. Which of the statements is known to be true according to the information provided?

A. The moon with radius R will have a greater radial acceleration than the moon with radius r.
B. The moon with radius R will have a longer orbital period than the moon with radius r.
C. The moon with radius R will have a greater mass than the moon with radius r.
D. The moon with radius R will have a greater speed than the moon with radius r.