After running for a while, the runner will usually get tired, and tend to run slower.
Time affects speed because if the time is frozen no one can run or a car does not have speed
Speed determines how long time the Runner needs to finish the race. For those actually competing, the one with the highest speed gets the shortest time and wins the race. For the recreational Runner, speed still determine the time. And since the race course is usually only open a limited time, even a recreational rider needs to keep the pace up.
No. The only thing that affects the passage of time is extreme speed, speeds very near the speed of light.
I cannot say about "lenght", but distance is a measure of length so length affects distance. Speed is the rate of change of distance (over time) so length affects speed. Mass does not significantly affect speed or distance but, because they are affected by acceleration and acceleration is affected by mass (for a given force), then mass affects them. Also, mass affects space time and the presence or absence of mass changes the lines along which distances are measured and so distances and speed are affected.
16.1 mph
Speed affects the frequency and pressure affects the wavelength.
the brakes affect the speed
Depends. Is it a distance run? Or a fast run? If it is distance, the stamina runner would win. If it was a track, then the speed runner would win.
Gravity affects the fabric of space-time. So both space and time will be distorted.
Assuming the runner maintains his average speed for an hour, 3 kilometres in 30 minutes is equal to 6 kilometres per hour.
their speed
The answer depends on the distance for the race. A marathon runner could not maintain the speed attained by a sprint runner.