Q1. Neil Armstrong was the first person to reach on the moon. While walking on the moon
(a) His mass remained the same but weight increased
(b) His mass remained the same but weight decreased
(c) His mass as well as weight decreased
(d) His mass increased but weight remained the same
(UPSC Prelims 1980)
Answer: (b) His mass remained the same but weight decreased
Explanation: Mass remains constant, but weight depends on gravity. Since the moon’s gravity is weaker, Neil Armstrong’s weight decreased, though his mass stayed the same.
Q2. Why does man weigh more at the poles than at the equator?
(a) Because there is no atmosphere at the poles
(b) Because gravitational pull is more at the poles
(c) Because gravitational pull is less at the poles
(d) None of the above
(UPSC Prelims 1981)
Answer: (b) Because gravitational pull is more at the poles
Explanation: The Earth is not a perfect sphere—it bulges at the equator and is flattened at the poles. This shape causes stronger gravitational pull at the poles, making a person weigh slightly more there than at the equator.
Q3. A man coming down on a lift leaves a ball from his hand. The ball will
(a) Go up
(b) Fall down
(c) Remain stationary with respect to man
(d) Oscillate up and down
(UPSC Prelims 1987)
Answer: (b) Fall down
Explanation: When the man releases the ball, it is subject to gravity, regardless of the lift’s motion. Hence, the ball will fall down, following the natural downward acceleration due to gravity.