Manipulate[
vx1 = v0;
r = 1;
g = 9.8;

If[vx1 * t ≤ 5,
x = vx1 * t - 5;
y = -1;
t1end = t;
];

If[vx1 * t ≥ 5 && y < 1 && x ≥ -1,
s = First@NDSolve[{r * theta''[t2] == -g * Sin[theta[t2]], theta[0] == 0, r * theta'[0] == v0}, theta[t2], {t2, 0, 10}];

x = Sin[theta[t2] /. s /. t2 -> t - t1end];
y = - Cos[theta[t2] /. s /. t2 -> t - t1end];
t2end = t;
];

If[y ≥ 0.98 && x > -5,
vx3 = Sqrt[v0^2 - 4 * g * r];
x = -vx3 * (t - t2end);
y = 1;
t3end = t;
];

If[vx1 * t ≥ 5 && x ≤ -5 && y ≥ -1,
vx4 = vx3;
x = -vx4 * (t - t3end) - 5;
y = -0.5 * g * (t - t3end)^2 + 1;
];
en = Circle[{0, 0}, 1];
sen1 = Line[{{-5, -1}, {0, -1}}];
sen2 = Line[{{-5, 1}, {0, 1}}];
ten = Disk[{x, y}, 0.1];
Graphics[{en, ten, sen1, sen2}, {PlotRange -> {{-6.2, 1.2}, {-1.2, 1.2}}}],
{t, 0, 10},{v0, 5, 7}
]