The acceleration due to gravity would be 2/9 of its old value.
Work Step by Step
Equation 5-5 gives g, the acceleration due to gravity near the surface of a planet such as Earth. If the mass were to double, this would increase g by a factor of 2.0. If the radius were to triple, this would decrease g by a factor of 9.0. Overall, g changes by a factor of 2/9.