1. The problem statement, all variables and given/known data The gravitational field strength of an unknown planet is 15.5 N/kg on its surface. Calculate the value of “g” if the planets mass and radius were both doubled. Hint: Use variation. 2. Relevant equations g= GM /R2 3. The attempt at a solution Well my teacher gave a hint saying use variation so this was my attempt at it: M / 2M = R2 / 2R2 Now this is where i kind of get stuck. If I simplify M, i am left with: 1/2 = R2 / 2R2 I don't now what i should do next or if i am even on the right track... Thanks in advanced!