2006 General Studies, all questions
UPSC Prelims 2006 · General Studies
Question 37: Geography
What is the approximate mean velocity with which the Earth moves round the Sun in its orbit?
a20 km/s
b30 km/s
c40 km/s
d50 km/s
AnswerThe answer is (b).
The Earth's orbit is nearly a circle about 150 million km in radius, so its length is about 2 x 3.14 x 150 million, roughly 940 million km. The Earth takes about 3.15 x 10 to the power 7 seconds (one year) to cover it. Dividing gives about 30 km/s, or roughly 108,000 km/h. Remember that figure: about 30 km/s.
Why each option is right or wrong
- (a) 20 km/s is too slow for the Earth's orbital speed.
- (b) Correct: the Earth moves at roughly 30 km/s around the Sun.
- (c) 40 km/s is too fast.
- (d) 50 km/s is far too fast.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2006, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.