How specifying data is code in the WolframAlpha Pro window. How avoid the limit in the caracters length ?The use of the paste and copy seems truncated. The interpreter is not understanding what is typed. Here is what is to be interpreted as instructions. I would like to plot the perihely of the ellipse solution for about 1000 seconds. ( and not one as specified {t, 0,1} g=9.8; l=16; AI=30 [Degree]; a=10^-6;

sol = NDSolve[{
   x''[t] == -g/l x[t] + a/l Cos[2 AI], 
   y''[t] == -g/l y[t] + a/l Sin[2 AI],
   x[0]==1., x'[0]==0, y[0]==y'[0]==0.}, {x, y}, {t, 0, 1}, 
   Method -> "ExplicitRungeKutta"];
ParametricPlot[Evaluate[{x[t], y[t]} /. sol], {t, 0, 1}]

Thank you to Bill Simpson for the previous reply.