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Question :
76. For any object orbiting the Sun, Kepler's Law may : 2102148

76. For any object orbiting the Sun, Kepler's Law may be written *T*^{2} = *kr*^{3}. If *T* is measured in years and *r* in units of the Earth's distance from the Sun, then *k* = 1. What, therefore, is the time (in years) for Mars to orbit the Sun if its mean radius from the Sun is 1.5 times the Earth's distance from the Sun?

A. 1.8 years

B. 2.8 years

C. 3.4 years

D. 4.2 years

77. In order for a satellite to be geosynchronous, its orbit must:

A. go over the North and South Poles.

B. be over the equator.

C. be over a single longitude.

D. emit television signals.

78. An asteroid is in orbit at 4 times the earth's distance from the Sun. What is its period of revolution?

A. one fourth year

B. 4 years

C. 8 years

D. 16 years

79. Doubling the mean distance from the Sun results in changing the orbital period of revolution by what factor?

A. 2^{1/2}

B. 2

C. 2^{3/2}

D. 2^{2}

80. The Earth's orbit is closest to the Sun in January and farthest from the Sun in July. When is the Earth moving the fastest in orbit?

A. Neither January nor July since the orbital speed of the Earth is a constant.

B. January

C. July

D. This occurs twice a year, in April and in October.