Always use your name for store id. It's most convenient. whenever you have some problems with product, they will ask you for id. So, its better to use real name. I often use some fictitious characters like Peter Parker, Ken Adams, etcetera while signing up on some timepass websites.
The gravitational potential energy near a planet is then negative, since gravity does positive work as the mass approaches. This negative potential is indicative of a bound state; once a mass is near a large body, it is trapped until something can provide enough energy to allow it to escape.
The kinetic energy is related to velocity by KE = 1/2 * mv^2 where m is the mass of the ball, and v is the velocity. Potential energy is related to height by PE = mgh where g is the acceleration of gravity (we can assume we're at the surface of the Earth, where g = 9.8 m/s^2), and h is height.