m=1;g=10;X=1;P=1;

X0P0tab={{0,0},{X/2,0},{X,0},{X,P/2},{X,P},{0,P}};

Pfun[t_,x0_,p0_]=p0+m g t;
Xfun[t_,x0_,p0_]=x0+p0/m t+1/2 g t^2;

Graphics[Polygon[Table[{Xfun[t,X0P0tab[[i]][[1]],X0P0tab[[i]][[2]]],Pfun[t,X0P0tab[[i]][[1]],X0P0tab[[i]][[2]]]},{i,1,Dimensions[X0P0tab][[1]]}]/.{t->.4}],Axes->True,AxesOrigin->{0,0},PlotRange->{{0,5},{0,10}}]

Animate[{Graphics[Polygon[Table[{Xfun[t,X0P0tab[[i]][[1]],X0P0tab[[i]][[2]]],Pfun[t,X0P0tab[[i]][[1]],X0P0tab[[i]][[2]]]},{i,1,Dimensions[X0P0tab][[1]]}]],Axes->True,AxesOrigin->{0,0},PlotRange->{{0,5},{0,10}}],(Xfun[t,X0P0tab[[3]][[1]],X0P0tab[[3]][[2]]]-Xfun[t,X0P0tab[[1]][[1]],X0P0tab[[1]][[2]]])(Pfun[t,X0P0tab[[6]][[1]],X0P0tab[[6]][[2]]]-Pfun[t,X0P0tab[[1]][[1]],X0P0tab[[1]][[2]]])},{t,0,1}]