Question

What will be the acceleration due to gravity whose mass is 8 times the mass of the earth and whose radius is twice that of earth.

Answer 1

acceleration due to gravity = GM/R^2 = G*8M/ (2R)^2 = 2GM/R^2 = 2g

Answer 2

$g = const \times m \div {r}^{2}$

g'

$= \frac{g \times 8}{ {2}^{2} } = 2g$