model massa "Componente massa"
  parameter Real m = 0.2;
  junta a, b;
  Real v;
equation
  m * der(v) = b.f - a.f;
  v = der(a.y);
  a.y - b.y = 0.0;
  annotation(Diagram(coordinateSystem(extent = {{-148.5, -105}, {148.5, 105}}, preserveAspectRatio = true, initialScale = 0.1, grid = {5, 5})));
end massa;