Re: [Paddlewise] Newtonian Physics

From: Michael Edelman <mje_at_spamcop.net>
Date: Wed, 31 Jul 2002 12:54:12 -0400
> From: "Peter Chopelas" <pac_at_premier1.net>
<I wrote>
>>Say our big fat WW paddle moves through the water twice as fast as the
>>boat to go 4mph:
> 
> 
>         8lbs * (5.87fps + 11.74 fps) = 140 ft-lb/sec = 0.256 HP.
><snip>


> Your model is wrong because you are comparing the wrong forces.  

Actually, it was a misstaement of Jeff's model. I was trying to show the 
errors.

Jeff's model actually stated Force = hull drag * (hull speed + slippage)

>...In both
> cases you used the resistance of the drag of the boat, 8 pounds, and then
> multiplied that by an assumed paddle speed.  You have to multiply the hull
> drag by the HULL speed and you get the power OUT-put. 

Right. Jeff multiplied drag * (hull speed + slippage) and called that 
force needed to propel the boat at V.

-- mike
-----------------------------------
Michael Edelman   medelman_at_ameritech.net
http://www.foldingkayaks.org
http://www.findascope.com



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Received on Wed Jul 31 2002 - 09:53:00 PDT

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