To: WSFAlist at keithlynch.net
Date: Tue, 7 Jan 2003 10:06:28 -0500
Subject: [WSFA] Re: baseballs and newsgroups
From: ronkean at juno.com
Reply-To: WSFA members <WSFAlist at keithlynch.net>

On Mon, 6 Jan 2003 23:22:00 -0500 (EST) "Keith F. Lynch"
<kfl at KeithLynch.net> writes:
> ronkean at juno.com wrote:
> > Can anyone calculate terminal velocity?  I suppose the question
> > is: how fast a wind would it take to exert 1.42 newtons of force on a

> > 43 cm^2 cross section?

>
> Not enough information.  The surface makes a big difference.
>

Yes, the surface can make a difference in the drag coefficient, as does
the shape.  A flat plate facing the wind can have some 30 times the drag
coefficient of an airfoil shape.  A golf ball is dimpled because the
dimples reduce drag compared to what the drag would be with a smooth
ball, such as a ping-pong ball.  But amazingly, for some shapes even
knowing the shape and surface does not necessarily determine the drag
coefficient.
See http://www.grc.nasa.gov/WWW/K-12/airplane/shaped.html .
At that web page it is said that a sphere may have a drag coefficient
anywhere from .07 to 0.5, depending on air speed.

But they do give a formula for drag, so now I can try to calculate the
upper and lower limits for the terminal velocity, assuming the baseball
is a sphere, and ignoring the effect of the surface characteristics, by
taking the drag coefficient of the baseball to be in the range .07 to 0.5
.

The formula given is D = 1/2 Cd R A V^2, where D is drag, Cd is drag
coefficient, R is air density, A is frontal area, and V is velocity.  To
find V, we may use
V = sqrt(2D / Cd R A).

So for Cd = 0.5, and R = 1.2, we get V = 33 m/s = 109 feet per second =
74 miles per hour.  For Cd = .07, we get 89 m/s = 199 miles per hour.  So
in round numbers the terminal velocity of a baseball would be somewhere
between 75 mph and 200 mph.

> ...there was the journalist who reported that
> there were many thousands of satanic cults on the Internet.  He had
> done a search for all web pages containing either "satanic" or
> "cult," and assumed that all such pages were home pages for distinct
groups
> of Satan worshippers.
>

Of course an actual satanic cult probably would not describe itself in
those words, 'cult' being a word which has acquired a pejorative
connotation.

... New York fan Seth Breidbart is the person who formally
> defined
> newsgroup spam for purposes of determining what should be canceled.
> Look up "Breidbart Index".)
>

That seems to be an index of 'excessive multiple posting' within a 45 day
period.

... Google
> also indexes over 3 billion web pages, something it's much better
> known for.
>
> And they do it *quickly*, too.  They're already indexed the
> November
> 1992 WSFA Journal, which I just put up yesterday, and didn't tell
> anyone about.  (Googling for "drunken badgers" will find it.)

But it seems to vary.  One of my neighbors built a Bonetti machine and
posted pictures of it on the web (I had made the pictures), and I readily
found those with a google search for "bonetti machine".  It was on the
first page of search results, out of some 1500 results.

http://users.erols.com/mbillian/Bonetti_machine/

But my own web page has been up for nearly a year, and google has
apparently not indexed it.

Ron Kean

.

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