The graph above shows the horizontal component of the velocity for the marble (dashed line) and the cannon (solid line) relative to the ground. Before time the marble-cannon system is at rest. At time the marble begins accelerating within the cannon, and at time the marble leaves the cannon. (i) Describe how to find the change in the distance between the center of mass of the cannon and the center of mass of the marble from time to time . Assume that before time the center of mass of the marble is at the same position as the center of mass of the cannon.