permaculture

[John Schinnerer <john@eco-living.net>]

Aloha,

> > Again...one PP is only a fraction of one MP (or HP), so they wouldn't be 
>
> Again, increase the veverage to make 1 MP = 1 HP.
...
>> If they could indeed turn it, it would take
>> ten+ times as long to do the same work.
>
> No so with gearing and aluminum pole/lever.

Yes, so! (do I sound like GW Bush yet? :-p)

Basic physics here...HP is a power quantity, not a work quantity, and 
PersonPower (PP) would be the same, a power quantity.

Basic equation is:

power = work / time

They can never be "the same" as quantities of power.  One person cannot 
expend as much power in a given time as one horse.
From the above,

work = power * time

...and the horse has more power available than the human for any given 
time interval.  So the horse can do a given amount of work in less time 
than a human.

One PP can certainly be applied to do the same amount of work as one HP, 
but not in the same amount of time.

For example the longer lever may make one person able to turn the mill 
that only a horse could turn before, but it also means they have a 
longer path to travel for every revolution of the mill.  So for a given 
number of revolutions of the mill, they are going to be walking farther 
(a lot farther) than the horse.

More on work, power, time on this page (as one example):

http://www.glenbrook.k12.il.us/gbssci/phys/Class/energy/u5l1e.html

cheers,
John S.

--

John Schinnerer - MA, Whole Systems Design
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