Plotted function returning unexpected result

Question

I am currently doing a little project which involves using a defined function. I set values for two terms, and I took the derivative and squared the two terms. When I attempt to plot it, I do not get anything in the window, nor do I get any errors. Here is what I have for code:

a = ((1/8)*(((0.1*t) - 3)^5)) - 0.5*(((0.1*t) - 3)^3)
b = ((0.1*t) - 3)^2
e = Sqrt[((a')^2) + ((b')^2)]

I receive the following output for the solution of "e"

Sqrt[(Derivative[1][(-0.5 (-3 + 0.1 t)^3 + 1/8 (-3 + 0.1 t)^5)])^2 + (Derivative[1][((-3 + 0.1 t)^2)])^2]

When I go to plot:

Plot[e, {t, 0, 60}, AspectRatio -> 0.5, Frame -> True]

I get a graph with no plot.

Is there something I am doing wrong? Any help would be appreciated.

Answer 1

   a = ((1/8)*(((0.1*t) - 3)^5)) - 0.5*(((0.1*t) - 3)^3)
   b = ((0.1*t) - 3)^2
   e = Sqrt[(D[a, {t, 1}]^2) + (D[b, {t, 1}]^2)]
  Plot[e, {t, 0, 60}, AspectRatio -> 0.5, Frame -> True, PlotStyle ->Blue, FrameStyle -> Directive[Black, Thick]]