ballz = NDSolve[{z''[t] == -9.81, z[0] == 5, z'[0] == 0,
WhenEvent[z[t] == 0.2, z'[t] -> -0.9 z'[t]]}, z, {t, 0, 10}];

bally = NDSolve[{y''[t] == 0, y[0] == -2, y'[0] == 4,
WhenEvent[y[t] == 4.8, y'[t] -> -0.9 y'[t]],
WhenEvent[y[t] == -4.8, y'[t] -> -0.9 y'[t]]}, y, {t, 0, 10}];

Manipulate[
  ParametricPlot3D[{t - 2, y[t] /. bally, z[t] /. ballz}, {t, 0, a},
    PlotStyle -> {Gray, Dashed, Thick},
    PlotRange -> {{-5, 5}, {-5, 5}, {0, 10}}],
  {a, 0.025, 10, 0.025}]