A $1300$ kg aircraft going $40$ m$/$s collides with a $3000$ kg aircraft that is parked and they stick together after the collision and are going $12\mathrm{.}1$ m$/$s after the collision. If they skid for $12\mathrm{.}5$ seconds before stopping, how far did they skid? Hint: Are the aircraft moving at a constant velocity after the collision or do they experience an acceleration?