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A geostationary satellite orbits around the earth in a circular orbit of radius 36 000 km. Then, the time period of a spy satellite orbiting a few hundred kilometres above the earth’s surface (Re = 6400 km) will approximately be(a) 1/2 h (b) 1 h (c) 2 h (d) 4 h |
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Answer» Correct Answer is: (c) 2 h For a satellite in a circular orbit around the earth, the time period T depends on the radius r as T2 ∝ r3. Here, for the geostationary satellite, T1 = 24 h and r1 = 36 000 km. For the spy satellite, r2 = 6400 km and time period = T2 . T22/T12 = r23/r13 or T2 = T1 (r2/r1)3/2 = (24 h)(6400 Km/36 000 Km)3/2 ≃ 2 h. |
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