Using a 2-D collision experiment: A marble is launched off a track and travels 28cm before it hits the floor. A marble is launched off a track and hits another marble at the end of that track, where both hit the floor. One lands 13cm away at 44° from the perpendicular and the other lands 22cm away at 41° from the perpendicular. I did the math and got the the correct answer, but then there is another question that asks "Explain why the displacement represents acceleration". I really have no idea how these to have anything in common. I know that the collision causes energy transfer causing the balls to go in a slightly different direction. Does anyone have any hints? Thanks.