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.
Mechanical energy is the sum of energy in a mechanical system, or any group of objects that interact based on basic mechanical principles. This includes both kinetic energy, the energy of motion, and potential energy, the stored energy of position.