Re: Language Challenge 2000

[Vincent DIEMUNSCH <vincent.diemunsch@edf.fr>]

Sorry, I made a mistake,
my" + Dsin(alfa) + mg = 0 is correct !


Vincent DIEMUNSCH a �crit :

> I have a few questions regarding the equations themselves :
>
> >Find the optimal initial angle for a trajectory to reach a target at
> >000 m to within .5 m. The equations of motion are given by,
> >
> >               mx" + Dcos(alfa) = 0
> >                my" + Dsin(alfa) + mg = 0
> >where
>  >               D = .5*Cd*A*rho(y)*v^2     alfa = atan(y'/x')
> >
> >and rho() is a variable atmospheric density w.r.t. altitude.
> >
> >Parameters:     m = 20 kg   Cd = .3   A = .02 m^2   g = 9.80665 m/s^2
> >Initial values: x = 0 m    y = 0 m   v = 180 m/s   alfa = 40 deg
>
> - What is the rho(y) function exactly ?
> - shoudn't it be my" + Dsin(alfa) - mg = 0   instead of  my" + Dsin(alfa) +
> mg = 0 ?
>
> And finally cos(atan(y'/x')) = x'/v and sin(atan(y'/x')) = y'/v, which will
> certainly speed up computing !!!
>
> >
> >
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