Find the radius of a spherical asteroid that has a density of 4600 kg/m3 and an acceleration due to gravity of 0.11 m/s2 at the surface.
km
F = GMm/r^2 = ma, so
a = GM/r^2
r^2 = GM/a
You have M and a, and can find G. So, plug and chug.
km
a = GM/r^2
r^2 = GM/a
You have M and a, and can find G. So, plug and chug.