When a body has a net force of 0 on it, one cannot say that it is at rest or in motion at a constant velocity.
If a body is accelerating because of some force and I want to stop it, I can apply the same force in the opposite direction. Unfortunately, that seems to mean that the body will start moving at the velocity it had when the opposite force was applied.
Does this mean that you cannot ever stop a body (generally, but specifically when the body has a constant acceleration) by applying an equal and opposite force?
How then do you stop such a body? You have to apply a force that keeps increasing in amount until the body comes to rest?