Running Speed Calculation for 62.5 kg Runner - 65.4 W Race

[nazarip]

While running, a person dissipates about 0.554 J of mechanical energy per step per kilogram of body mass. If a 62.5 kg runner dissipates a power of 65.4 W during a race, how fast is the person running? Assume a running step is 1.50 m in length.

Well I know that the person loses 34.6 J of mech energy every 1.5 m and loses a total of 65.4 watts during the entire race. Now 65.4 W is just 65.4 J/s, so how can I further relate all of these givens? I am a little confused. Thanks for any help in advance.

 

[maverick280857]

In one step, the amount of energy dissipated is given by

$$(62.5kg)(0.554Jkg^{-1})$$ (per step or per 1.50m)

Suppose there are n steps. This corresponds to a distance 1.50n meters. Hence in n steps the energy dissipated per unit time is

$$(62.5)(0.554)(n) = 65.4$$

from this you can get the number of steps he covers in unit time. Multiply it by 1.50m to get the speed. Is this okay?

cheers
vivek

 

[nazarip]

Thanks for the help.