Step-by-step explanation:
he ran 100m in 9.58 seconds.
that speed is then
100/9.58 m/s
in what scales or dimensions do we need to specify this speed ?
if we need it in m/s (meaning how many meters in 1 second), then we just just do the division :
100/9.58 = 10.43841336... m/s
if we need it in km/h (kilometers per hour), we need to remember that
1 hour = 60 minutes = 60×60 seconds = 3600 seconds.
so, we need to multiply
10.43841336/1 by 3600/3600 to get the speed measured in 1 hour.
10.43841336... × 3600 = 37,578.2881... m/h
to get km/h we need to remember that 1 km = 1000 m.
so, this is
37,578.2881.../1000 = 37.5782881... km/h
how do we know that the top speed must have been higher ?
because this is a mean value across the whole 100 m.
and he did not do a flying start (already running full speed when approaching the start). he started with 0 speed and accelerated during the first part of the race - during this phase he was for sure slower than the mean speed we calculated above.
so, in order to compensate for the initial slower speeds (to achieve the calculated mean value), he must have been faster than that during other parts of the race, so that the mean value was then what we calculated.