Why Velocity is considered over speed to calculate momentum or acceleration?
This is a reasonable question. Direction and point of origin may or may not matter, depending on what questions you are trying to answer. For example, if you are trying to determine the amount of impact force during a head-on collision, you can do that by just considering the relative _speed_ of the two objects and how the speed changes during the impact (without regard to an origin point or to the particular orientation of the line on which they’re travelling). But for other types of momentum problems, the direction of the velocity really does matter. For example, suppose you were given this question: “Two trucks of equal mass, both travelling at 50 km/h, collide, and stick together after the impact. At what speed do the combined trucks travel after impacting?” This sort of question cannot be solved without considering the relative _directions_ in which the trucks were travelling before impact. If they collide head on, their post-impact speed is zero. If they collide at a 90-degree an
