The radii of two planets A and B are R and 4 R and their densities are ρ and ρ 3 respectively. The…

The radii of two planets A and B are R and 4R and their densities are ρ and ρ3 respectively. The ratio of acceleration due to gravity at their surfaces gA:gB will be
 
  1. 4:3
  2. 1:16
  3. 3:16
  4. 3:4

Solution

Acceleration due to gravity is written as g=GMr2=G×43×π×r3×ρr2=4πG3ρr 

Given:

 rA=RrB=4RρA=ρρB=ρ3

Hence, the ratio is 

gAgB=R×ρ4R×ρ3=34.

Asked in: JEE Main 2023 (11 Apr Shift 1)

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