A ball is projected horizontally from the top of a building. One second later, another ball is projected horizontally from the same point with the same velocity. (a) At what point in the motion will the balls be closest to each other? the instant the second ball is projected the instant the first ball hits the ground They stay equidistant from each other throughout the motion. one second after the second ball is projected (b) Will the first ball always be traveling faster than the second? Yes No (c) What will be the time difference between them when the balls hit the ground? It depends on the height of the building. no time difference one second between one and ten seconds (d) Can the horizontal projection velocity of the second ball be changed so that the balls arrive at the ground at the same time?