program gjhg;
uses graph;
const n=100;
       h=10;
       g=9.8;
       m=4;
       l=15;
       v=10;
       p=1000;
       c=2;
       k=3;
var driver,mode,i,,j:integer;
var tm,fi0,fi1,w1,w0,t,dt:real;
f,e:text;
begin
dt:=0.00001;
tm:=20;
fi0:=pi/6;
w0:=0;
assign(f,'dta');
rewrite(f);
assign(e,'atd');
rewrite(e);
while t<tm do
begin
if sin(fi0)<=(h/l) then
            begin
            w1:=w0+(dt/sqr(l)/m)*(-c*fi0-m*g*sin(fi0)*l);
            fi1:=fi0+w0*dt;
            fi0:=fi1;
            w0:=w1;
            t:=t+dt;
            end
            else begin
                 w1:=w0+(dt/m/sqr(l))*(-c*fi0-m*g*sin(fi0)*l-k*w0*sqr(l));
                 fi1:=fi0+w0*dt;
                 fi0:=fi1;
                 w0:=w1;
                 t:=t+dt;
                 end;
                 j:=j+1;
                 if j mod 1000=0 then
                   begin
                      writeln(e,t,fi1);
                      writeln(f,t,w1);
                      j:=0;
                  end;
end;
close(f);
close(e);
end.