Your story has to include one part of constant forward motion, one part of constant backward motion and a period of stationary. For the part of forward motion, it has at least to be 10 seconds time duration with a minimum of 100 meter in length. For the part of backward motion, it must be at least 5 seconds time duration with a minimum of 50 meter in length. The object has to stop at least for 5 seconds during the direction changes. During the whole motion, the object has to stay on a straight line.