1. The problem statement, all variables and given/known data Find the altitudes above the Earth's surface where Earth's gravitational field strength would be (a) two-thirds and (b) one-third of its value at the surface. [Hint: First find the radius for each situation; then recall that the altitude is the distance from the surface to a point above the surface.] 2. Relevant equations I do believe i use F=Gm1m2/r^2 3. The attempt at a solution Well, actually im at a little loss for this question..