Physics
posted by Deanna .
While running, a person dissipates about 0.6 J of mechanical energy per step per kilogram of body mass. If a 60kg person runs with a power of 70 Watts during a race, how fast is the person running? Assume a running step is 1.5 m long.

70 J/s = (V/1.5)step/s*(0.6 J/step kg)*60 kg
Solve for V in meters/s
V = 70*1.5/(0.6*60) = 2.9 m/s
That is a pretty slow speed for a runner. It's roughly 9 minutes miles... more like jogging. 
Thank you!

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