# Gravitation help..........thanks

posted by
**Jessy** on
.

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

(a) As a multiple of Earth's radius RE, what is the radial distance a projectile reaches if its initial speed is one-fifth of the escape speed from Earth?

____ times RE

(b) As a multiple of Earth's radius RE, what is the radial distance a projectile reaches if its initial kinetic energy is one-fourth of the kinetic energy required to escape Earth?

_____ timesRE

(c) What is the least initial mechanical energy required at launch if the projectile is to escape Earth?

P.S.Bobpursley, sorry,I don't really understand the last question you answered....