You’re probably right, the longest phase of the race is getting up to top speed which is after about 50-60m (a bit further for Bolt because it’s actually strides) and then they start to slow down again. The 60m WR is 6.34s, assume that Bolt isn’t as fast as that (he’s not the record holder /we know his height makes him generally a slow starter) so he’d be slower than 6.34s to the 60m mark and then does the last 40m in about 3.something seconds. So I agree, the speed is likely to still be more than 10m/s at the line.
IDK in the 200, by the same logic they can’t be at full sprint but same calc would say 6.34s to 60m and then 140m in 13s or so. Practically pedestrian ;-), but the inefficient first 50m is then outweighed by more at speed.
I’d never realised that – average speed for the 200m WR is almost identical to the 100m WR. I wonder what the flying 100m time in the middle of a 200m is?