Re: Air Resistance

[brian whatcott <inet@intellisys.net>]

At 05:51 12/11/97 -0800, John Mallinckrodt wrote:
> On Wed, 10 Dec 1997, LUDWIK KOWALSKI wrote:
>
> > The  reference for the empirical formula: "Analytical Mechanics" by 
> > G.R. Fowles and G.L. Cassiday, Fifth Edition, 1993, page 62. It is the
> > usual c1*v+C2*v^2 description. For a sphere of diameter D the empirical
> > values are:  c1=1.55*10^-4*D and c2=0.22*D^2, all in SI units.
>
> It's worth noting that the empirical formula implies that quadratic drag
> becomes dominant at speeds greater than (7 x 10^-4)/D (in SI units).  For
> Ludwik's basketball this is about 3 mm/s, about 600 times less than the
> smallest velocity reported. ...
> A. John Mallinckrodt 

There is a helpful plot in EncBrit 15th ed. given in Streeter's article,
Mechanics, Fluid   Macropaedia Vol 11, p791 under the Drag heading.
This shows the drag of spheres.

This is cast in the usual aerodynamic terms - a log/log plot of Drag 
Coefficient vs. Reynold's Number.
 This seems to show that the sphere used in our experiment is beginning to
experience steeply reducing drag with the transition from laminar flow to
a turbulent boundary layer. Golf, anyone?  

Sincerely

brian whatcott <inet@intellisys.net>
Altus OK