Re: Energy of a foot step


"gb6726" <gb6726@xxxxxxxxx> wrote in message
news:1191537544.290248.132910@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Sorry, I asked somebody else and he calculated about 7 watts if a
foot
step
is made by a 75 kilogram person once a second. Watt-s.

Woops. 7 watt-h if he steps once a second. Ok now.

Therefore the answer is: "7 watt". I worked together with electrical
engineers.

If the question is "Energy of a foot step", then it is 7 watts-h/3600
watts. Oh yeah, it is 7 watt-s.



I can only get a simlar answer if I assume the displacement is 1cm. For
example someone walking on a 1cm thick pressure matt from which the energy
is extracted..

Energy = mass x g x displacement

so the energy in a single step is:

Energy = 75 x 9.8 x 0.01

= 7.35 Watt Seconds (or joules if you prefer)

Then..

Power = Energy/time

so the average power during the step is

= 7.35 / 1
= 7.35 Watts

If the person kept that up for an hour that would be 7.35 Watt Hours of
energy. This assumes that the energy produced is continuous. A runner (for
example) has both feet off the ground for part of the stride so that might
be a factor.



.

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