Manipulate[
 (*by Nasser M. Abbasi, June,17,2014*)
 tick;
 Module[{y, data},
  (*solution of eq=m y''[t]+c y'[t]+k y[t]\[Equal] -m g;*)
  y = Chop[1/(2 k Sqrt[c^2 - 4 k m])
      g m (-c E^(((-c - Sqrt[c^2 - 4 k m]) t)/(2 m)) + c E^(((-c + Sqrt[c^2 - 4 k m]) t)/(2 m)) - 2 Sqrt[c^2 - 4 k m] + 
       E^(((-c - Sqrt[c^2 - 4 k m]) t)/(2 m)) Sqrt[c^2 - 4 k m] + E^(((-c + Sqrt[c^2 - 4 k m]) t)/(2 m)) Sqrt[c^2 - 4 k m])];
  If[y < -7,
   If[wasHit,
    wasHit = False;
    y = -6.95,
    wasHit = True;
    y = -7]
   ];
  
  data = rugo[-3, 0, -3, L0 + y - massThickness];
  If[runningState == "RUNNING",
   t = t + delta;
   If[t > 999.9, t = 0];
   tick = Not[tick]
   ];
  Grid[{
    { Row[{"Time ", padIt2[t, {5, 2}]}]},
    {
     Graphics[
      {
       {EdgeForm[Black], LightGray, Rectangle[{-4, L0 + y - massThickness}, {4, L0 + y + massThickness}]},
       Line[{{2, 0}, {2, 1}, {2.5, 1}, {2.5, 1.5}}],
       Line[{{2, 1}, {1.5, 1}, {1.5, 1.5}}],
       Line[{{1.6, 1.2}, {2.4, 1.2}}],
       Line[{{1.6, 1.3}, {2.4, 1.3}}],
       Line[{{2, 1.3}, {2, L0 + y - massThickness}}],
       {Thick, Line[{{-6, 0}, {6, 0}}]},
       Line[data]
       }, PlotRange -> {{-5, 5}, {-1, 11}}, Axes -> False, ImageSize -> 300, ImagePadding -> 5
      ]
     }
    }
   ]
  ],
 
 Grid[{
   {"damping",
    Manipulator[Dynamic[c, {c = #, t = 0} &], {0, 1, 0.01}, ImageSize -> Small], Style[Dynamic@padIt2[c, {3, 2}], 11]
    },
   {"stiffness",
    Manipulator[Dynamic[k, {k = #, t = 0} &], {1, 100, 0.01}, ImageSize -> Small], Style[Dynamic@padIt2[k, {5, 2}], 11]
    },
   {"mass",
    Manipulator[Dynamic[m, {m = #, t = 0} &], {1, 10, 0.01}, ImageSize -> Small], Style[Dynamic@padIt2[m, {4, 2}], 11]
    },
   {Text@Style["slow", 11],
    Manipulator[Dynamic[delta, {delta = #} &], {0.01, .1, 0.01}, ImageSize -> Small, ContinuousAction -> False], 
    Text@Style["fast", 11]
    },
   {Grid[{
      {
       Button[Style["run", 12], {runningState = "RUNNING"; tick = Not[tick]}, ImageSize -> {55, 35}],
       Button[Style["stop", 12], {runningState = "STOP"; t = 0; tick = Not[tick]}, ImageSize -> {55, 35}]
       }
      }
     ]
    }
   }
  ],
 {{wasHit, False}, None},
 {{m, 1}, None},
 {{k, 10}, None},
 {{c, 0}, None},
 {{runningState, "STOP"}, None},
 {{t, 0}, None},
 {{delta, 0.01}, None},
 {{tick, True}, None},
 TrackedSymbols :> {tick},
 Initialization :>
  (
   g = 9.8; L0 = 10; massThickness = 0.5;
   
   (*definitions used for parameter checking*)
   integerStrictPositive = (IntegerQ[#] && # > 0 &);
   integerPositive = (IntegerQ[#] && # >= 0 &); numericStrictPositive = (Element[#, Reals] && # > 0 &); 
   numericPositive = (Element[#, Reals] && # >= 0 &); numericStrictNegative = (Element[#, Reals] && # < 0 &); 
   numericNegative = (Element[#, Reals] && # <= 0 &);
   bool = (Element[#, Booleans] &);
   numeric = (Element[#, Reals] &);
   integer = (Element[#, Integers] &);
   padIt1[v_?numeric, f_List] := 
    AccountingForm[Chop[v], f, NumberSigns -> {"-", "+"}, NumberPadding -> {"0", "0"}, SignPadding -> True]; 
   padIt2[v_?numeric, f_List] := 
    AccountingForm[Chop[v], f, NumberSigns -> {"", ""}, NumberPadding -> {"0", "0"}, SignPadding -> True]; 
   padIt2[v_?numeric, f_Integer] := 
    AccountingForm[Chop[v], f, NumberSigns -> {"", ""}, NumberPadding -> {"0", "0"}, SignPadding -> True];
   
   rugo[xkezd_, ykezd_, xveg_, yveg_] := 
    Module[{step = 20, szel = 1(*spring width*), hx, hy, veghossz = 0.3, hossz, dh, i}, {hx = xveg - xkezd;
       hy = yveg - ykezd;
       hossz = Sqrt[hx^2 + hy^2];
       dh = (hossz - 2*veghossz)/step;
       {xkezd, ykezd}}~Join~{{xkezd + hx*(dh + veghossz)/hossz, ykezd + hy*(dh + veghossz)/hossz}}~Join~
      Table[If[OddQ[i], {xkezd + hx*(i*dh + veghossz)/hossz + hy*szel/hossz, 
         ykezd + hy*(i*dh + veghossz)/hossz - hx*szel/hossz}, {xkezd + hx*(i*dh + veghossz)/hossz - hy*szel/hossz, 
         ykezd + hy*(i*dh + veghossz)/hossz + hx*szel/hossz}], {i, 2, (step - 2)}]~
      Join~{{xkezd + hx*((step - 1)*dh + veghossz)/hossz, ykezd + hy*((step - 1)*dh + veghossz)/hossz}}~Join~{{xveg, yveg}}];
   )
 ]