Just like Rossolll to put a spin on this topic ........
gus


> On Feb 9, 2010, at 4:26 AM, Russell McMahon wrote:
>
> Dateline Dalan, bove Shnzhen, below Guanzho - this messge was found  
> while
> serching for something more prosaic :-).
>
> People have died jumping from high altitude.
> Terminal velocity is approximately proportional to inverse air  
> density.
> Energy rises as V^2.. Air density drop logarithmicaly, halving about  
> every
> 4500 metres (from memory). Combine all tyhat and you can get extremely
> energetic at high altitudes. Then, go into  spin. Not recommended.  
> I'm told
> that ams and legs have detached. Lose consciousness and you probaby  
> die.
> Maintaining stability is extxremely desirable.
>
> FWIW teriminal velocity can be found close enough by rarranging:
>
> Force = Falling mss x g = 0.5 x Rho x A x V^2 x k
>
> So Vtermianl ~~~~= sqrt(2mg/*Rhjo.A.k)
> A = frontal area and k is drag coefficinet - strt with 1 for a flat  
> plate.
>
> As Rho tends to zero V tends to nasty
>
> Rho starts at 1.3 kg/m^3 at sea level and decreases as above.
>
>         Russel;
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