As we know, velocity to escape from an orbit is in proportional with the orbital velocity:
$$v_\mathrm{escape}=\sqrt{2}v_\mathrm{orbit}$$
Since, orbital velocity decreases as we move away so should be velocity to escape from it. In other words farther is an orbit lesser will be velocity to escape from it.
Thus, as we move away the value of velocity with which we need to escape decreases. Now isn't that actually negative acceleration? We need to have that acceleration in order to escape.
Why then we call it as escape velocity instead of escape acceleration?
(And, if I am correct is it just opposite of gravitational acceleration?)
Best Answer
I think the issue is a lot clearer if you think in terms of energy. When you're on the surface of the Earth, you're in a gravitational potential well. You need a certain amount of kinetic energy to "climb out" of the potential well, and since velocity is a visible (and less abstract) proxy for kinetic energy, it's common to speak of escape velocity.