- Etot < 0:
- Kinetic Energy < Potential Energy
- object is bound to the system
- circular, elliptical orbits
- Etot = 0:
- Kinetic Energy = Potential Energy
- just enough kinetic energy to reach infinity
- defines "escape velocity"
- orbit is a parabola
- Etot > 0:
- Kinetic Energy > Potential energy
- object easily escapes system
- orbit is a hyperbola
