>

 

Mostly we did math on the board today.  

>	with(DEtools): phug:= [ diff(theta(t),t) = ( v(t)^2 - cos(theta(t))) / v(t),         diff(v(t),t)     = -sin(theta(t)) - R*v(t)^2 ];

 

>

 

(1)

 

>	R:=1; DEplot(phug, [ theta(t), v(t) ], t=0..40,

 

>	[[theta(0)=0, v(0)=2.5], [theta(0)=0, v(0)=.8]],

 

>	theta=-Pi/2..3*Pi, v=0..3,

 

>	linecolor=[blue,red], stepsize=0.1);

 

>