How do I do it similarly for a ball hitting the floor at y=0?

You just need kinematics for this. May be something like this? (this was for a HW assignment, so code is not very clean. Did it in about 3 hrs). Most of the code deal with handling the state of the running simulation (reset, stop, step, etc...) if you do not care about all of this, you can remove all that and the code will shrink to 10% of its current size.

Manipulate[
 tick;
 h = 1;
 g = 9.8;
 If[(statex == "RUN" || statex == "STEP") && statex2 == "",
  If[state == "down",
   delS = currentV*delT + 1/2 g delT^2;
   currentV += g *delT;
   currentH -= delS
   ,
   delS = currentV*delT - 1/2 g delT^2;
   currentV -= g *delT;
   currentH += delS
   ];
  distantTravelled += delS
  ];

 gr = Graphics[
   {
    Line[{{-.3, -r/2}, {.3, -r/2}}],
    (*{LightGray,Dashed,Line[{{0,0},{0,1}}]},*)
    {Red, Disk[{0, currentH}, r]}
    },
   PlotRange -> {{-.3, .3}, {-4 r, 1 + 4 r}}, Axes -> {False, True}, 
   ImageSize -> {300, 300}];
  gr = Grid[{
    {Grid[{
       {"height", "speed", "cycle #", "\[CapitalDelta]s", "direction"},
       {padIt2[currentH, {3, 2}], padIt2[currentV, {4, 3}], padIt2[n, {1}], 
        padIt2[delS, {4, 3}], state}
       }, Frame -> All]
     },
    {Grid[
      {
       {Column[{"Theoretical", "total time"}], Column[{"Current", "time"}], 
        Column[{"Theoretical", Column[{"total", "distant"}]}], 
        Column[{"current", "distance"}]},
       {padIt2[tTime, {6, 3}], padIt2[currentT, {6, 3}],
         padIt2[tDistance, {3, 2}], padIt2[totalDist, {6, 3}]
        }
       }, Frame -> All
      ]
     },

    {gr, SpanFromLeft}}];

 If[statex2 == "pass",
  statex2 = ""
  ,
  currentT += delT;
  totalDist += delS;
  If[Abs@distantTravelled >= maxH,
   distantTravelled = 0;

   If[state == "down",
    currentV = e*currentV;
    state = "up";
    n = n + 1;
    maxH = e^(2*n)*h;
    currentH = 0
    ,
    state = "down";
    currentV = 0;
    currentH = maxH
    ]
   ]
  ];

 If[statex == "RUN" && currentT < tTime,
  tick = Not[tick]
  ];
 gr,
 {{tick, False}, None},
 Text@Grid[{
    {Grid[{
       {Button[Text@Style["run", 12], {statex = "RUN"; tick = Not[tick]}, 
         ImageSize -> {50, 40}],
        Button[Text@Style["step", 12], {statex = "STEP"; tick = Not[tick]}, 
         ImageSize -> {50, 40}],
        Button[Text@Style["stop", 12], {statex = "STOP"; tick = Not[tick]}, 
         ImageSize -> {50, 40}],
        Button[
         Text@Style["reset", 12], {statex = "STEP"; currentH = 1; 
          currentT = 0; n = 0;
          distantTravelled = 0; currentV = 0; maxH = 1; state = "down"; 
          totalDist = 0; statex2 = "";
          tDistance = If[e == 1, Infinity, (1 + e^2)/(1 - e^2)];
          tTime = If[e == 1, Infinity, Sqrt[2/9.81]*((1 + e)/(1 - e))];
          tick = Not[tick]}, ImageSize -> {50, 40}]}
       }, Frame -> True, FrameStyle -> Gray
      ], SpanFromLeft},
    {Grid[{

       {"Coefficient of restitution",
        Manipulator[Dynamic[e, {e = #;
            statex = "STEP";
            currentH = 1;
            currentT = 0; n = 0;
            distantTravelled = 0;
            currentV = 0;
            maxH = 1;
            state = "down";
            totalDist = 0;
            tDistance = If[e == 1, Infinity, (1 + e^2)/(1 - e^2)];
            tTime = If[e == 1, Infinity, Sqrt[2/9.81]*((1 + e)/(1 - e))];
            tick = Not[tick];
            statex2 = "pass"} &], {0, 1, .01}, ImageSize -> Tiny], 
        Dynamic[padIt2[e, {2, 2}]],
        SpanFromLeft},

       {"Animation speed",
        Manipulator[Dynamic[delT, {delT = #} &], {0.001, 0.03, 0.001}, 
         ImageSize -> Tiny], Dynamic[padIt2[delT, {3, 3}]],
        SpanFromLeft},

       {"ball size",
        Manipulator[
         Dynamic[r, {r = #; tick = Not[tick], statex2 = "pass"} &], {0.01, 
          0.1, 0.001}, ImageSize -> Tiny], Dynamic[padIt2[r, {3, 3}]],
        SpanFromLeft}

       }, Alignment -> Left, Frame -> True, FrameStyle -> Gray]
     }}],
 {{n, 0}, None},
 {{currentH, 1}, None},
 {{currentT, 0}, None},
 {{state, "down"}, None},
 {{statex, "STEP"}, None},
 {{statex2, ""}, None},
 {{distantTravelled, 0}, None},
 {{currentV, 0}, None},
 {{maxH, 1}, None},
 {{gr, 0}, None},
 {{e, .9}, None},
 {{delT, 0.02}, None},
 {{r, 0.04}, None},
 {{totalDist, 0}, None},
 {{tDistance, (1 + (.9)^2)/(1 - (.9)^2)}, None},
 {{tTime, Sqrt[2/9.81]*((1 + .9)/(1 - .9))}, None},
 TrackedSymbols :> {tick},
 Alignment -> Center,
 SynchronousUpdating -> True,
 SynchronousInitialization -> True,
 FrameMargins -> 1,
 ImageMargins -> 1,
 ControlPlacement -> Left,
 Initialization :>
  {
   padIt1[v_, f_List] := 
    AccountingForm[Chop[v], f, NumberSigns -> {"-", "+"}, 
     NumberPadding -> {"0", "0"}, SignPadding -> True];
   padIt2[v_, f_List] := 
    AccountingForm[Chop[v], f, NumberSigns -> {"", ""}, 
     NumberPadding -> {"0", "0"}, SignPadding -> True]
   }
 ]