NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Wind & Current Navigation
From: Dan Allen
Date: 2003 Apr 17, 14:57 -0700
From: Dan Allen
Date: 2003 Apr 17, 14:57 -0700
On Thursday, April 17, 2003, at 02:08 PM, George Huxtable wrote: > Now for Dan's fair question: why the square? > > Let's consider something like a dustbin-lid on a long bridle, towed far > behind an immersed submarine. It makes no difference whether it's the > bin-lid moving through the water, or a water-current impinging on the > lid. > If the speed doubles, then in a given time twice as much water > impinges on > the lid. And with the speed doubled, every drop (or every molecule or > every > gram) of that water has twice as much momentum (which is mass x > velocity) > which it gives up to the lid when it's brought to a stop. Force is > given by > the rate of transfer of momentum, so we get the force increased by 2 x > 2 = > 4. Is that good enough to satisfy Dan, or does he wish to get more > fundamental? More fundamentals! Teach us hydrophysics! Dan
