Question

A hypothetical planet has density $\rho$ radius R, and surface gravitational acceleration g. If the radius of the planet were doubled, but the planetary density stayed the same, the acceleration due to gravity at the planet's surface would be?

Answer 1

acceleration due to gravity,$g=\frac{GM}{R^2}$

Mass of the planet $=v\times d$

$M=\frac{4}{3}\pi G{R}^{3}d$

$g=\frac{4}{3}\pi GRd$

Acceleration of gravity depends on both R and density,So the gravity is 2g.