Question

If the earth were the same size but twice as massive, what would be the value of G? What would be the value of g? (Let your equation g = Gm/d2 guide your thinking.)

Answer 1

The value of G would be the same as it is a constant of our universe, the value of g would increase twice:

$$g=\frac{G(2M)}{d^2}=19.6\text{ m/s}^2.$$