more samples for Modelica language,

see issue #2486

samples/Modelica/Pendulum.mo

@@ -0,0 +1,47 @@
+within ModelicaByExample.Subsystems.Pendula;
+model Pendulum "A single individual pendulum"
+  import Modelica.Mechanics.MultiBody.Parts;
+  import Modelica.Mechanics.MultiBody.Joints;
+
+  parameter Modelica.SIunits.Position x;
+  parameter Modelica.SIunits.Mass m "Mass of mass point";
+  parameter Modelica.SIunits.Angle phi "Initial angle";
+  parameter Modelica.SIunits.Length L "String length";
+  parameter Modelica.SIunits.Diameter d=0.01;
+
+  Parts.Fixed ground(r={0,0,x}, animation=false)
+    annotation (Placement(
+        transformation(
+        extent={{-10,-10},{10,10}},
+        rotation=270, origin={0,60})));
+  Parts.PointMass ball(m=m, sphereDiameter=5*d)
+    annotation (Placement(transformation(extent={{-10,-90},{10,-70}})));
+  Parts.BodyCylinder string(density=0, r={0,L,0}, diameter=d)
+    annotation (Placement(transformation(
+        extent={{-10,-10},{10,10}},
+        rotation=90,
+        origin={0,-30})));
+  Joints.Revolute revolute(phi(fixed=true, start=phi),
+    cylinderDiameter=d/2, animation=false)
+    annotation (Placement(
+        transformation(
+        extent={{-10,-10},{10,10}},
+        rotation=90,
+        origin={0,20})));
+equation
+  connect(string.frame_a, ball.frame_a) annotation (Line(
+      points={{0,-40},{0,-40},{0,-80}},
+      color={95,95,95},
+      thickness=0.5,
+      smooth=Smooth.None));
+  connect(revolute.frame_b, ground.frame_b) annotation (Line(
+      points={{0,30},{0,40},{0,40},{0,50}},
+      color={95,95,95},
+      thickness=0.5,
+      smooth=Smooth.None));
+  connect(revolute.frame_a, string.frame_b) annotation (Line(
+      points={{0,10},{0,10},{0,-20},{0,-20}},
+      color={95,95,95},
+      thickness=0.5,
+      smooth=Smooth.None));
+end Pendulum;