the world's current population is 7.3 billion and the world population in 1915 was 1.8 billion. The increase over the past century is 7.3 billion - 1.8 billion = 5.5 billion. So, the correct answer would be "more than 5 billion" (option D).
Answer:
Answered
Explanation:
(i) 1 Astronomical Unit (A.U.) = 1.496 x 10^8 Km.
Therefore, distance of Voyager I from Earth = 71 AU = 71 x 1.496 x 10^8 = 1.062 x 10^10 Km.
(ii) The nearest star to Earth than sun is the Proxima Centauri in the Alpha Centauri system. The Proxima Centauri is 4.22 light years away from Earth.
As, 1 Light year = 63241.1 AU
The distance of the Proxima Centauri from Earth = 4.22 x 63241.1 AU = 266877.3 AU
The distance of the Voyager I from Earth = 71 AU
The number of times the distance of the Proxima Centauri from Earth is greater than that of Voyager I is = 266877.3 / 71
= 3758.835 times.
(iii) Speed of light is 1.079 x 10^9 Km/hr
Light travels 1.079 x 10^9 km in 1 hr
Therefore, 1. 062 x 10^10 Km is traveled by light in = (1.062 x 10^10) / (1.079 x 10^9) hr = 9.84 hours
That means when Voyager I was 71 AU from Earth, a observational data from Voyager I at the speed of light took 9.84 hours to reach Earth.
I think B because it involved friction
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