Question

The diameters of two planets are in the ratio 4 : 1 and their mean densities in the ratio 1 : 2. The acceleration due to gravity on the planets will be in ratio

• A. 1 : 2
• B. 2 : 3
• C. 2 : 1
• D. 4 : 1

Answer 1

Answer: (C)

2 : 1

Answer 2

$g = \frac { 4 } { 3 } G \pi R \rho$ $\Rightarrow \frac { g _ { 1 } } { g _ { 2 } } = \frac { \rho _ { 1 } R _ { 1 } } { \rho _ { 2 } R _ { 2 } }$ $= \frac { 1 } { 2 } \times \frac { 4 } { 1 } = \frac { 2 } { 1 }$