Weight and g: two planets have the same surface gravity, but planet b has twice the mass of planet a. if planet a has radius r, what is the radius of planet b

the radius of planet B is times the radius of planet A

Explanation:

The surface gravity of a planet is given by

where

G is the gravitational constant

M is the mass of the planet

R is the radius of the planet

For the two planets in the problem, we have:

(same gravity)

(planet B has twice the mass of planet A)

So we can write

so, the radius of planet B is times the radius of planet A.