f[x_] := Sin[x]*x/2; SS1 = Plot[f[x], {x, -3, 3}, DisplayFunction ->  Identity];
SS2[u_] := Graphics[{Blue, PointSize[0.03], Point[{u, f[u]}]}];
SS3[u_] := Graphics[{Red, Arrow[{{u, f[u]}, {u + 1*A1, f[u] +  f'[u]*A1}}]}];
SS4 := Graphics[{Red, FontSize -> 30, Text["How Fast you Go", {0,  1.8}]}];

Manipulate[If[r == 1, A1 = .5];
  If[r == 2, A1 = 1]; If[r == 3, A1 = 1.5]; If[r == 4, A1 = 3];
  Animate[Show[{SS1, SS2[u], SS3[u], SS4}, PlotRange -> {{-3, 3}, {0,  2}},
    Axes -> False], {u, -A1*5, A1*5}], {{r, 1,
    "Choose your Transportation Means:"}, {1 -> "Horse", 2 -> "Car",
    3 -> "Plane", 4 -> "Space Shuttle"}}]