Question

Calculate the minimum area moment of inertia for a rectangular cross-section with side lengths 3 cm and 8 cm.

Answer 1

Lx = b h^3 /12

Ly= b^3 h/ 12

Where:

Lx= Area moment of inertia related to the x axis

Ly= Area moment of inertia related to the y axis

b= base = 3 cm

h= height = 8 cm

Replacing:

Lx = 3 (8)^3 / 12 = 3 (512) /12 = 128 cm^4

Ly= 3^3 * 8 / 12 = 27 (8) / 12 = 18 cm^4

Answer = 18 cm4