# Kinematic Concepts - Mission KC8 Detailed Help The velocity-time data sets below represent the motion of four objects. Which data set(s) depict(s) a negative acceleration? List all that apply ... . Direction of Acceleration: Acceleration is a vector quantity and it has a direction. For an object moving in a straight line, the direction of the acceleration is dependent upon two factors:   the direction that the object moves, and whether the object is speeding up or slowing down   If an object is speeding up, then the direction of the acceleration is in the same direction that the object is moving. If an object is slowing down, then the direction of its acceleration is in the opposite direction that the object is moving. One way for an object to have a negative acceleration is to move in the positive direction and slow down. Such an object has a positive velocity and a negative acceleration. (Incidentally, the other way to have a negative acceleration is to move in the negative direction and speed up.) In this question, each object has a positive velocity. So in this case the object(s) with negative acceleration is (are) slowing down; their magnitude of velocity is decreasing.  