Correct Answer - Option 3 : Section modulus
Explanation:
The strength of two beams of the same material can be compared by the section modulus values.
The beam is stronger when section modulus is more, the strength of the beam depends on section modulus.
The strength of the beam also depends on the material, size, and shape of cross-section.
Section modulus of a beam can be expressed as
\({\sigma _b} = \frac{M}{Z}\)
Therefore,
\(Z = \frac{M}{{\sigma _b}}\)
where Z is the section modulus and found out as \(Z = \frac{I}{y}\)
\(Z=\frac{I}{y}=\frac{\frac{\pi d^4}{64}}{\frac{d}{2}}={\frac{\pi d^3}{32}}\)
Strength of the beam ∝ Z ∝ d3
