UPSC Prelims 2001 · General Studies
Question 109: Science and Technology
The mass of a body on Earth is 100 kg (acceleration due to gravity, gₑ = 10 m/s²). If acceleration due to gravity on the Moon = gₑ/6, then the mass of the body on the moon is
AnswerThe answer is (c).
Mass is the amount of matter in a body and does not change with place, so its mass on the Moon is still 100 kg. Only its weight changes: on the Moon it weighs one-sixth of its Earth weight, about 167 newtons against 1,000 newtons on Earth, using g = 10 m/s2. Remember that mass is constant while weight depends on g.
Why each option is right or wrong
- (a) This is one-sixth of the mass, confusing mass with weight.
- (b) Sixty kg has no basis; mass does not change.
- (c) Right: mass stays 100 kg.
- (d) Mass does not increase by a factor of six.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2001, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.