para = {R1 ->  P, M1 ->  P L,  
        h -> (E^(-s))}
para1 = {P ->  1, L ->  1}
para2 = {DiracDelta[L] ->  0, UnitStep[L] ->  1, 
        UnitStep[-L] ->  0}

example 7.8  p. 155

fs = PowerExpand[R1 - M1 s - P h^L /. para]

qs = Expand[fs/s]
qx = InverseLaplaceTransform[qs, s, x]
% /. x ->  L /. para2

ms = qs/s;
mx = InverseLaplaceTransform[ms, s, x]
% /. x ->  L

Plot[{qx /. para1, mx /. para1}, {x, 0, 1}, 
      PlotRange -> {{0, 1},  {-1, 1}}, 
      PlotStyle ->  {Hue[0.9], Hue[0.7]}, 
      AspectRatio ->  0.3]

yx = 
      InverseLaplaceTransform[-ms/s^2, s, x]
yx /. x ->  L

Plot[-yx /. para1, {x, 0, 1}, 
      PlotRange -> {{0, 1},  {-0.5, 0}}, 
      PlotStyle ->  Hue[0.9], AspectRatio ->  0.3, 
      GridLines ->  Automatic]