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Question :
61. A satellite in a circular orbit about the Earth : 2102145

61. A satellite is in a circular orbit about the Earth at a distance of one Earth radius above the surface. What is the speed of the satellite? (The radius of the Earth is 6.4 ´ 10^{6} m, and *G* = 6.67 ´ 10^{-11} N?m^{2}/kg^{2}.)

A. 2 800 m/s

B. 4 200 m/s

C. 5 600 m/s

D. 16 800 m/s

62. A careful photographic survey of Jupiter's moon Io by the spacecraft *Voyager 1* showed active volcanoes spewing liquid sulfur to heights of 70 km above the surface of this moon. If the value of *g* on Io is 2.0 m/s^{2}, estimate the speed with which the liquid sulfur left the volcano.

A. 260 m/s

B. 530 m/s

C. 790 m/s

D. 970 m/s

63. If the mass of Mars is 0.107 times that of Earth, and its radius is 0.530 that of Earth, estimate the gravitational acceleration *g* at the surface of Mars. (*g*_{earth} = 9.80 m/s^{2})

A. 2.20 m/s^{2}

B. 3.73 m/s^{2}

C. 4.20 m/s^{2}

D. 5.50 m/s^{2}

64. The escape speed from the surface of the Earth is 11.2 km/s. Estimate the escape speed for a spacecraft from the surface of the Moon. The Moon has a mass 1/81 that of Earth and a radius 0.25 that of Earth.

A. 2.5 km/s

B. 4.0 km/s

C. 5.6 km/s

D. 8.7 km/s

65. Geosynchronous satellites orbit the Earth at a distance of 42 000 km from the Earth's center. Their angular speed at this height is the same as the rotation rate of the Earth, so they appear stationary at certain locations in the sky. What is the force acting on a 1 500-kg satellite at this height?

A. 85 N

B. 333 N

C. 404 N

D. 457 N