Needs["Graphics`PlotField`"];
l=100;
modell={u'[s]== v[s],
v'[s]== -u[s]- 0.1 v[s],u[0]==u0, v[0]==v0};
p:=Module[{},loesung=NDSolve[modell,{u,v},{s,0,l}]; 
abb=ParametricPlot[Evaluate[{u[s],v[s]}/.loesung],{s,0,l},
DisplayFunction->Identity,
PlotPoints->50]
];
bild[1]={u0=0;v0=1;p};
feld=PlotVectorField[{z2,-z1-0.1 z2},{z1,-1,1,0.25},{z2,-1,1,0.25},
DisplayFunction->Identity,PlotRange->{{-1,1},{-1,1}}];
abb0=Show[Evaluate[bild[1],feld],
DisplayFunction->$DisplayFunction,
PlotRange->{{-1,1},{-1,1}},AxesLabel->{"x","y"},ImageSize->{400,300}];
Export["c:\\buch.neu\\Teubner_Vieweg2\\reibung02.eps",abb0];
Export["c:\\buch.neu\\Teubner_Vieweg2\\reibung02.wmf",abb0];