If the mass of the Sun were ten times smaller and the universal gravitational constant were ten times larger in magnitude, which of the following is not correct?
- Raindrops will fall faster.
- Walking on the ground would become more difficult.
- Time period of a simple pendulum on the Earth would decrease.
- g on the Earth will not change.
Answer
(4) g on the Earth will not change.
Solution
Acceleration due to gravity on the Earth: g = GMERE2 (it does not depend on the mass of the Sun).
G becomes 10 times ⇒ g' = 10g ⇒ g on the Earth increases, so statement (4) is not correct.
(1) Terminal speed of a raindrop vt = 2r2( - )g9 g ⇒ raindrops fall faster — correct.
(2) Weight mg increases ⇒ walking becomes more difficult — correct.
(3) T = 2 lg ⇒ T decreases — correct.
Answer: (4)