How can I use manipulate to control many functions with many variables?

Question

I am new to mathematica so i ve trying to solve many equations with different variables using manipulate. So what i have written so far is the following.

Manipulate[
  n = 98.5/100;
  Q = 8050;
  W = 5.2;
  H = 6.1;
  L = 4.1;
  ap = 2*H*L;
  A = -Q/W*Log[1 - n];
  N = A/ap + ns;
  R = ns*L/H;
  nd = N - 1;
  u = Q/(nd*D*H);
  aa = 2*H*L*ns*nd;
  Show[{N, R, nd, u, aa}],
  {{ns, 2, Row[{"tmimata sti roi ", Text@Style["ns", Italic]}]}, 2, 8, 1, Appearance -> "Labeled"}, 
  {{D, 0.15,Row[{"Diakeno plakwn ", Text@Style["D", Italic]}]}, 0.15, 0.4,0.05, Appearance -> "Labeled"}]

After all of what i have mentioned the results i am getting are all fault. Please, any help is much appreciated.

Answer 1

This gets rid of the errors.

Not a good idea to use variables with UpperCase first letter. In particular, you used N and D which are Mathematica own symbols.

If you want to use a variable with one letter and wanted that be an UpperCase, then good idea to add 0 to it, as in N0, D0, H0.

Also you used Show when there is no graphics. Use Grid for formatting.

Manipulate[

 n = 98.5/100;
 Q0 = 8050;
 W0 = 5.2;
 H0 = 6.1;
 L0 = 4.1;
 ap = 2*H0*L0;
 A0 = -Q0/W0*Log[1 - n];
 N0 = A0/ap + ns;
 R0 = ns*L0/H0;
 nd = N0 - 1;
 u = Q0/(nd*D0*H0);
 aa = 2*H0*L0*ns*nd;

 Grid[{{N0, R0, nd, u, aa}}, Frame -> All],

 (*control variables below *)
 {{ns, 2, Row[{"tmimata sti roi ", Text@Style["ns", Italic]}]}, 2, 8, 
  1, Appearance -> "Labeled"},

 {{D0, 0.15, Row[{"Diakeno plakwn ", Text@Style["D", Italic]}]}, 0.15,
   0.4, 0.05, Appearance -> "Labeled"}

 ]