There's several threads on this topic, but the following points are pertinent:
You generally have a warm-up on the treadmill to accelerate up to the minimum constant speed required to complete the distance in 10 minutes.
The absolute minimum constant speed required, assuming you have a flying start over the distance is 14.5Km/h to complete it under ten minutes. A flying start at 16 Km/h constant over the distance will return a time of 8 mins.
The way to work it out is by the rule of sixes (handy for Speed Time Distance AIB questions)
If you run at 16 Km/h, in a tenth of an hour (6 mins) you will cover 1.6Km. To cover 2.4Km, a third more of six is 2 mins. Making 8 mins for 2.4Km.
If you run at 14.4Km/h, in a sixth of an hour (10 mins) you will cover 14.4Km divided by 6 which is 2.4Km. In other words, 10 mins dead, but you want to do it under 10 mins so 14.5Km/h is a safe constant speed .
Basic calculation for it is Speed = Distance ÷ Time
The frontal driving wheel is a specific known size and spins spins so many times a second depending on the speed and that number of rotations can determine the distance travelled by the moving running surface (the rubber mat that rotates) a simple timer shows the amount of time you have had the treadmill running and the speed is variable.
That answer your question. Or where you looking for what speed to run at for your PJFT?