If the density of earth is doubled keeping its radius constant, then acceleration due to gravity (g) =

20 m/s2 10 m/s2 5 m/s2 2.5 m/s2

20 m/s2

$g=\frac{GM}{R^2}=G \frac{4}{3} \pi \frac{R^3 \rho}{R^2}=\frac{4}{3} \pi GR \rho, g \propto \rho g$ If $\rho$ is doubled g is doubled ∴  $g^{\prime}-20 ms^{-2}$