Q.

The radii of two planets 'A' and 'B' are 'R' and '4R' and their densities are ρ and ρ/3 respectively. The ratio of acceleration due to gravity at their surfaces (gA:gB) will be           [2023]

1 1 : 16  
2 3 : 16  
3 3 : 4  
4 4 : 3  

Ans.

(3)

g=GMR2=GR2×ρ×4π3R3=(4π3G)ρR

gAgB=R×ρ4R×ρ3=34