[ExI] Graphene power?

[John Clark]

On Tue, Nov 28, 2017 at 11:24 AM, Will Steinberg <steinberg.will at gmail.com>
wrote:

​> ​
> Well, the wind can go in the same direction twice, but we still can
> harness energy from it because of our point of view relative to it.  Is
> this similar?
>

It's not just any sort of energy we want, only one form of it, work, is
useful and work is force over distance. So we could rig a windmill
​ to a
pulley
​so it would​
 raise a weight
​,​
and that would create potential energy we could get work out of. If the
wind blew north as often as it blew south the wind would just as easily
raise the weight as lower it unless we put a ratchet on the pulley forcing
it to turn in only one direction
​, then​
 we could still get work out of it. That works fine if things are large and
slow moving but its impossible even in theory to make a perfect ratchet
​,​
 the smaller the ratchet and faster the force changes direction the more
often that ratchet i
​s​
going to slip.
​T​
hat's why a Brownian ratchet
​
would fail so often you could never extract work from random thermal
vibrations. Feynman made all this precise in one of his lectures:

http://www.feynmanlectures.caltech.edu/I_46.html


John K Clark
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