Q: Two planets have the same average density but their radii are R1 and R2. If acceleration due to gravity on these planets be g1 and g2 respectively, then

(a) $\frac{g_1}{g_2} = \frac{R_1}{R_2}$

(b) $\frac{g_1}{g_2} = \frac{R_2}{R_1}$

(c) $\frac{g_1}{g_2} = \frac{R_1^2}{R_2^2}$

(d) $\frac{g_1}{g_2} = \frac{R_1^3}{R_2^3}$

Ans: (a)