Compute all parts of given question:

Question: A projectile is shot directly away from Earth's surface. Neglect the rotation of Earth.

Part I: What multiple of Earth's radius RE gives the radial distance a projectile reaches if

(a) Its initial speed is 0.500 of the escape speed from Earth and

(b) Its initial kinetic energy is 0.500 of the kinetic energy required to escape Earth?

Part II: What is the least initial mechanical energy required at launch if the projectile is to escape Earth?

Explanation and formulas needed for best answer!