Assume a planet is a uniform sphere of radius R that (somehow) has a narrow radial tunnel through its center. Also assume we can position an apple...

Assume a planet is a uniform sphere of radiusRthat (somehow) has a narrow radial tunnel through its center. Also assume we can position an apple anywhere along the tunnel or outside the sphere. LetFRbe the magnitude of the gravitational force on the apple when it is located at the planets surface. How far from the surface is there a point where the magnitude of the gravitational force on the apple isFR/2 if we move the apple

(a)away from the planet and