NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Need dip-throw a rock?
From: Tom Sult
Date: 2011 Jun 22, 21:10 -0500
From: Tom Sult
Date: 2011 Jun 22, 21:10 -0500
For a relatively higher bridge would you expect a larger or a smaller error. I am thinking that the time to push the button is constituent and the total time is greater resulting in a smaller error. If you let go a few of those steel balls into the ocean from a hight of say 30 meter what might one expect? Thomas A. Sult, MD 3rd Opinion 1415 First First St. South #5 Willmar, MN 56201 320 235 2101 Office www.3rdOpinion.us tsult@mac.com On Jun 22, 2011, at 5:58 PM, Bill Morris wrote: > I thought I would discover how well the rock-throwing method might > work for me in practice. To avoid discussion about the behaviour of > feathers and the shape of rocks, I used petanque balls. These are > polished steel balls of 72 mm diameter and weighing 500 grammes, > used in the game of petanque (q.v.). > > I threw them horizontally from the bridge of our ship > "Baradozic" ("Little Paradise" in the Breton language - my wife is > from Brittany)and used a stop watch reading to 0.01 second to time > their fall onto level ground a measured 5.8 metres below. > > The mean time of 25 throws was 1.29 seconds, with a standard > deviation of 0.087 seconds, so that we could expect 95 percent of > the times to fall in the range 0.95 to 1.63, as indeed they > comfortably did (1.04 to 1.47). > > Taking the local acceleration due to gravity to be 9.805 metres/s/s > gives a height of 8.16, an error of nearly 30 percent. This would > give a dip error of 0.8 arcmin. > > The error is in the right direction. If one assumes a timing error > of 0.1 seconds (and you don't have to be old and decrepit to have > such an error when operating a stop watch), we get a much closer 6.9 > metres. > > The linked photograph shows the bridge of the Baradozic ;-)> > > Bill Morris > Pukenui > New Zealand > ---------------------------------------------------------------- > NavList message boards and member settings: www.fer3.com/NavList > Members may optionally receive posts by email. > To cancel email delivery, send a message to NoMail[at]fer3.com > ---------------------------------------------------------------- > >