Ferrous : NonFerrous : Polymers : Ceramics : Bolts : Springs : Thermodynamics : Bending : Stress
W = Force (N)
L = Length (mm)
M = Bending
Moment (Nmm)
y = Distance from Neutral axis to fiber  usually extremity (mm)
E = Young's Modulus or Mod of Elasticity (convert to MPa)
I = 2nd Moment of Area or Area Moment (mm4)
Z = Section Modulus (mm3) = I / y
Bending Stress = M*y / I = M / Z (MPa) which is maximum tension (or compression) at bottom (or top) of beam.
If column is "slender" it is likely to buckle when in compression.
Shape 
Ic(Centroidal 2nd Moment of Area) 
Centroid(Centre of Area) 
Area

RectangleBending about centroid (centre).
b = breadth, h = height 
At centre  A = b*h  
CircleBending about centroid (centre).
r = radius 
At centre  A = ∏*r2  
TriangleBending about centroid.
b = breadth, h = height 
Xc = h/3 Yc = b/3 
A = 0.5*b*h 
http://en.wikipedia.org/wiki/List_of_moment_of_areas