An airport tug is towing a baggage train at 8.0 m/s. The driver's reaction time is 0.75 s. In a test, the stopping distance of the tug at this speed is 22 m. Later, the same driver drives the tug at 4.0 m/s with the same load and the same braking force.
Calculate the stopping distance of the tug at 4.0 m/s.