Question

Two spheres of masses m and M are situated in the air and the gravitational force between them is F. The space around the masses in now filled with a liquid of specific density 3. The gravitational force will now be:

• A. 3F
• B. F
• C. $\frac{F}{3}$
• D. $\frac{F}{9}$

Answer 1

Answer: (B)

F

Answer 2

Gravitational force does not depend on the medium.
In this case time of flight of a ball ≥ 2 × 2 = 4 sec.
∴ Time of flight = 2u/g ≥4
$\Rightarrow$ u ≥ 2g $\Rightarrow$ u ≥ 19.6 m/s (∴g = 9.8 m/s2)