a physics question... I don't know actually
10k is about 6 miles. I walk about a 20 minute mile if everything is working right. Should take about 2 hours. Of course, I'll need to add on the time I used to stop into starbucks for a mocha along the way.
I speed-walk 5KM in 54 minutes and that is increment of speed during that time. At that point, I can then speed-walk 1KM in the six remaining minutes thereafter because I am warmed up and working out at my personal max. At that rate, then I could walk 10KM in 1 Hour 24 Minutes, but that is tough-going. What I do is set out to speed-walk 5KM in the fastest possible time rather than spend a set one hour work-out on the treadmill; in other words ... 5KM or one hour ... whichever comes first, but it never is one hour.
What some tend to forget is that it is easier for a 6 foot tall guy to go the distance than it is for a 5 foot 5 inch tall guy.