In astrodynamics a Δ "v" or delta- "v" (literally "change in velocity") is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver.
In astrodynamics a Δ "v" or delta- "v" (literally "change in velocity") is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver.