While running, a person dissipates about 0.60 J of mechanical energy per step per kilogram of body mass. If a?

Question

While running, a person dissipates about 0.60 J of mechanical energy per step per kilogram of body mass. If a 70 kg person develops a power of 78 W during a race, how fast is the person running? (Assume a running step is 1.5 m long.)

m/s

Answer 1

0.6J/step*kg x 70kg x Nsteps = E in joules = W*secs = (78W)*t

V = Nsteps/sec x 1.5m/ step = N*1.5 m/s

Doesn't seem we have enough info, but lets consider a time of 1 second.

In 1 sec,

0.6J/step*kg x 70kg x Nsteps = (78W)*1sec

N = 78/(0.6*70) = 1.86 steps

which means 1.86 steps/sec

1.86 steps/sec x 1.5m/step = 2.79 m/s