Students will use a spark timer to record the motion of two toy cars. The spark timer produces a physical record of the motion by making a mark on tape at set intervals. Students measure the distance between the marks and graph the motion. For constant velocity motion, the marks on the tape will be evenly spaced. The position vs. time graph will be a straight line with positive slope. The velocity vs. time graph will be a horizontal line. The pull-back car will accelerate and then decelerate. The acceleration will appear on the position vs. time graph as a parabola, and on the velocity vs. time graph as a line with positive slope.