I read that the the energy of an Oort cloud object is approximately zero, as in the potential energy plus the kinetic energy is equal to zero. I was also told that the radius was approximately infinite and the velocity is approximately zero. I understand why the radius is said to be infinite (since it is so far away from the Earth, it's radius from the itself to the earth is treated as infinite). However, what I do not understand is why the velocity of the Oort cloud object is zero. Any help on understanding why this is the case?