Question

The diameters of two planets are in ratio $4:1$. Their mean densities have ratio $1:2$. The ratio of '$g$' on the planets will be:

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

Answer 1

The correct option is C $2:1$

As, $g=\frac{2}{3}\pi GD\rho$

Therefore, $\frac{g_1}{g_2}=\frac{D_1{\rho }_1}{D_2{\rho }_2}=\frac{4}{1}\times \frac{1}{2}=\frac{2}{1}=2:1$